NCCA ASCII Polygraph Data Format: Complete Technical Guide

The Problem: Proprietary Data Silos in Polygraph Testing

Before 2009, the polygraph industry operated with a fundamental interoperability problem. Each of the four major North American polygraph instrument manufacturers — Axciton, Lafayette, Limestone, and Stoelting — stored examination data in completely proprietary file formats [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. A chart recorded on a Lafayette system was entirely inaccessible to anyone using a Limestone ParagonX, a Stoelting CPS, or an Axciton system. There was no universal way to share, review, or aggregate polygraph data across platforms.

This siloing created severe practical problems across the profession. Federal agencies operating polygraph programs that used multiple manufacturers' instruments could not aggregate or compare data from different platforms. Quality control reviewers were forced to maintain licenses for every vendor's software simply to open files from different examiners. Researchers studying polygraph validity were locked into whichever vendor's system had generated the original data, making large multi-site studies extremely difficult to conduct. This inability to share raw physiological data between platforms also meant that cross-validation of polygraph scoring algorithms was nearly impossible.

Perhaps most critically, valuable examination data risked becoming permanently inaccessible whenever a manufacturer updated their software architecture or discontinued a legacy product line — not a hypothetical concern given the industry's history of platform changes.

The Solution: A Universally Readable Export Format

In 2009, the Threat Analysis and Strategic Support (TASS) Branch of what was then the Defense Academy for Credibility Assessment (DACA) — the institution redesignated as the National Center for Credibility Assessment (NCCA) in August 2010 [2]Verified Congressional Record: Recognizing the National Center for Credibility Assessment (NCCA)
Confirms redesignation of DACA as NCCA in 2010 and institutional history — formally requested that all North American polygraph instrument manufacturers include a standardized data export feature in their software platforms.

The NCCA traces its origins to 1951, when it was first established as the U.S. Army Polygraph School [3]Verified Brand Name: NCCA Ribbon-Cutting Set for Today
Confirms NCCA was first established in 1951 as the Army Polygraph School and redesignated from DACA. Over the decades the institution evolved through several names: the DoD Polygraph Institute (DoDPI, 1986–2007), the Defense Academy for Credibility Assessment (DACA, 2007–2010), and finally the National Center for Credibility Assessment (NCCA) from 2010 onward [4]Verified National Center for Credibility Assessment — Polygraph UK Glossary
Confirms complete name history: Army Polygraph School (1951-1962), USAMP (1975-1986), DoDPI (1986-2007), DACA (2007-2009), NCCA (2009+). Today it falls under the Defense Counterintelligence and Security Agency (DCSA) and serves as the premier federal educational center for polygraph and other credibility assessment technologies [5]Verified NCCA Home — National Center for Credibility Assessment
Confirms NCCA's mission as the government's premier educational center for polygraph and credibility assessment technologies.

The NCCA ASCII specification was designed by two highly respected figures in polygraph research: Dr. John Kircher and the late Dr. Andrew (Andy) Dollins [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. The APA editorial staff specifically acknowledged their contributions, noting it was grateful to "John Kircher and the late Andy Dollins for their work in creating and coding the NCCA ASCII format" [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Dr. Kircher was widely recognized as a co-inventor of the first computerized polygraph system, developed alongside Dr. David Raskin at the University of Utah in 1991 [6]Verified Converus Announces the Passing of Dr. John Kircher
Confirms Dr. Kircher co-invented first computerized polygraph in 1991 with Dr. Raskin and passed on November 18, 2025. He passed away on November 18, 2025, following a battle with cancer [7]Verified John Kircher Obituary
Confirms Dr. Kircher passed in 2025 and created the first computerized polygraph. Dr. Dollins was a researcher affiliated with DoDPI/NCCA who contributed to numerous polygraph studies [8]Verified Comparison of Polygraph Data — Pollina, Dollins, Senter, Krapohl, Ryan
Confirms Dr. Andrew B. Dollins as a researcher at the Department of Defense Polygraph Institute.

The design philosophy prioritized simplicity and universality above all else. Rather than creating a complex binary format or requiring special parsing software, they chose plain ASCII text — the most universally readable digital format in existence. The resulting specification captures all hardware metadata, software version information, physiological time-series data, event timing, and question text for each chart in a format that any text editor, spreadsheet program, or statistical analysis environment can parse without specialized tools [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Publication and APA Mandate

The formal specification was published as "Introduction to the NCCA ASCII Standard" by Handler, M. and Hernandez, N. in Polygraph & Forensic Credibility Assessment: A Journal of Science and Field Practice, Volume 48, Issue 2, pages 125–135, in 2019 [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details[9]Verified APA PDF — Introduction to the NCCA ASCII Standard
Original PDF confirming Volume 48, Issue 2, pages 125-135, and acknowledgment of Kircher, Dollins, and Nelson. By that time, all four major manufacturers had already implemented support in their software, and the format had been in practical use across federal agencies for a decade.

The significance of this standard was formally cemented in August 2023 when the American Polygraph Association approved the APA Standard for Polygraph Instrumentation [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate. This standard was approved on August 25, 2023 and became effective September 1, 2023 [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate. It explicitly states that each instrument shall support the importation of recorded information from and exportation to a standardized cross-platform data format, specifically identifying the NCCA ASCII Standard as the required specification [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate. The standard references the NCCA ASCII publication as "Editorial Staff (2019). Introduction to the NCCA ASCII Standard. Polygraph & Forensic Credibility Assessment, 48(2): 125-135" [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate. Compliance with the APA Instrumentation Standard is voluntary but strongly encouraged, representing an important step toward universal data compatibility. Examiners pursuing continuing education should familiarize themselves with these requirements.

Four Fundamental Advantages of the NCCA ASCII Format

The NCCA ASCII Standard delivers four critical advantages for the polygraph profession, law enforcement, and research:

Cross-Platform Interoperability: Charts can be exported from any system and imported into any other. Examinations recorded on Lafayette hardware are viewable in Limestone, Axciton, or Stoelting software environments. Stoelting's CPSpro Fusion software, for example, can import data from Axciton, Lafayette, or Limestone systems exported in compatible formats [11]Verified CPSpro Fusion Software — Stoelting
Confirms Fusion can import Axciton, Lafayette, or Limestone data exported in pREFORMAT. This interoperability is essential for agencies operating multi-vendor environments.

Advanced Research: Raw physiological data becomes accessible for feature extraction, machine learning, signal processing, and algorithmic analysis beyond traditional visual scoring methods. The format supports sophisticated computational approaches to polygraph data analysis, including the development and validation of algorithms like PolyScore, OSS-3, and ESS-M [12]Verified Polygraph Scoring Algorithms Compared: PolyScore, OSS-3 & CPS
Foundational research relevant to understanding the algorithms that process NCCA ASCII data.

Future-Proof Data: As a plain text format, NCCA ASCII files never become obsolete. Data remains readable regardless of software updates, vendor changes, or discontinued products — a critical safety net for examination records that may be needed for legal proceedings or quality reviews years after the original test.

Quality Control: The format enables independent review, scoring comparison, and program evaluation across multi-vendor environments. This capability is essential for federal QC programs and for maintaining the high standards of in-person polygraph testing that the APA requires.

Impact on Polygraph Science and Machine Learning

The NCCA ASCII Standard fundamentally changed the trajectory of polygraph research. Before standardization, the polygraph field struggled to build large, representative datasets for validating scoring algorithms. Each agency's data existed in isolation on its own vendor platform.

With NCCA ASCII, data can now be aggregated from dozens of agencies using different hardware, processed through unified analysis pipelines, and used to train and validate new computational scoring methods. This capability has become increasingly important as the polygraph field explores machine learning and artificial intelligence approaches to credibility assessment. Research into advanced detection paradigms — including P300-based concealed information testing, which has demonstrated large effect sizes (d = 1.59) in meta-analysis [13]Verified The Concealed Information Test — Utilizing P300 Data
Meta-analysis found large mean effect size (d = 1.59) for P300-based CIT detection — benefits enormously from standardized data formats that enable cross-platform dataset aggregation.

Statistical approaches to polygraph data analysis continue to evolve. Hierarchical Bayesian models, for instance, have been applied to CIT data to provide more accurate effect size estimates than conventional methods, confirming validity across multiple physiological measures [14]Verified Hierarchical Bayesian Modeling for Time Series Physiological Data During the CIT
Hierarchical Bayesian models applied to 167 participants' CIT data provided more accurate effect size estimates. The NCCA ASCII format's structured, machine-parseable design makes it ideally suited for these advanced analytical approaches.

Core Design Principles

The NCCA ASCII format is deliberately simple by design. It uses a plain ASCII text file with no tab characters — because tab-character spacing varies among data-viewing programs and can corrupt column alignment [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Data columns are right-justified with fixed widths, and the structure is consistent enough that any text editor, spreadsheet application, or statistical programming environment can parse it reliably.

Each file represents one chart from one examination [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. A typical polygraph examination with three series and four charts per series would generate twelve separate NCCA ASCII files. Understanding how many chart runs a polygraph exam requires is important context for working with these files. This one-chart-per-file approach ensures that each file is self-contained and complete, carrying all the metadata needed to understand the data without reference to external files or databases.

The file contains four major sections in order: (1) a structured file name that identifies the manufacturer, examination, and chart number at a glance; (2) header metadata including instrument type, software version, date, time, channel configuration, and sampling rates; (3) an event list with precise sample-number timing for every question or stimulus event; and (4) the raw multi-channel physiological data matrix in fixed-width, right-justified columns.

How NCCA ASCII File Names Are Constructed

Every NCCA ASCII file name follows a strict, standardized pattern that encodes key identification information [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. The name begins with the uppercase letter "D", followed by a manufacturer symbol — a single special character unique to each vendor — a hyphen, the originating examination identifier, another hyphen, and a series/examination number encoded in hexadecimal. The file extension indicates the chart number within that examination and always ends with the letter "A" to designate it as an ASCII format file.

The four manufacturer symbols are: $ (dollar sign) for Axciton, & (ampersand) for Lafayette, % (percent) for Limestone, and # (hash) for Stoelting [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

The series/examination number uses hexadecimal encoding: digits 1 through 9 represent examinations 1 through 9, then A=10, B=11, C=12, D=13, E=14, and F=15. This allows up to 15 distinct examination types to be encoded within a single character position. For systems that do not differentiate between examination types in their internal architecture (Axciton and older Stoelting-DOS systems), the letter "X" is used as a fixed placeholder.

File Name Examples by Manufacturer

D$-$$$$ZG14-X.03A — Axciton system, Exam X, Chart 3. The Axciton-specific examination identifier uses their internal encoding, and "X" serves as the fixed examination type since Axciton does not differentiate exam types in file names.

D&-175-802-20050106 MGQT-2.01A — Lafayette system, Exam 2, Chart 1. Lafayette encodes the full examination name and date in the file identifier, providing rich context directly in the file name. Learn more about Lafayette's system capabilities in our LXEdge Software Platform guide.

D%-2007-13-1.01A — Limestone system, Exam 1, Chart 1. Limestone uses a year-based numbering scheme for the examination identifier. Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022 [15]Verified Limestone Technologies — Lafayette Instrument Company
Confirms Limestone became a subsidiary of Lafayette Instrument Company in August 2022.

D#-00001-X.02A — Stoelting system, Exam X, Chart 2. Older Stoelting-DOS systems use "X" similar to Axciton, while newer Stoelting Windows versions can encode examination-specific identifiers using the standard hexadecimal convention.

Understanding Each Header Field

The header records the instrument platform using standardized strings: "Lafayette Windows", "Axciton DOS", "Axciton Windows", "Limestone Windows", "Stoelting DOS", or "Stoelting Windows" [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. This immediately identifies the manufacturer and operating system environment that generated the data.

The software version follows the manufacturer's own versioning scheme (e.g., "11.8.3.218" for Lafayette LXSoftware), which is critical for identifying potential bugs or version-specific export behaviors. Dates use the DDMMMYY format (e.g., "12Aug19") with time recorded in military (24-hour) notation [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

The header records the total number of questions presented during the chart, the total number of samples in the data matrix, and the number of active channels. Critically, the header includes per-channel sampling rates in Hertz. Different channels may legitimately sample at different rates within the same recording. For example, respiratory channels might record at 10 Hz while cardiovascular and movement channels capture data at 60 Hz [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

The "Fastest Sample Rate" field records the highest rate among all channels — this determines the temporal resolution of the data matrix. The specification sets a maximum output sampling rate of 120 Hz [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Instruments that acquire data at higher native rates — such as Limestone's ParagonX at 625 samples per second per channel [16]Verified ParagonX Polygraph System — Limestone
Confirms native 625 samples per second per channel — highest sampling rate in any polygraph instrument — must downsample to at most 120 Hz for the NCCA ASCII export. The APA Instrumentation Standard separately mandates a minimum data acquisition rate of 25 samples per second [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate.

How Event Timing Works in the NCCA ASCII Format

The event list section records every stimulus event presented during the chart — typically the questions asked during a polygraph examination. The section is divided into two parts: the event label section (listing question identifiers and full text) and the event timing section (listing precise sample numbers for each event's onset, offset, and answer) [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Event labels occupy columns 07 through 14 (right-justified within an 8-character field). The question text begins at column 16 and can extend to column 80, providing 65 characters per line. Questions longer than this limit continue on the next line starting at column 16, ensuring no question text is truncated regardless of length [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Understanding proper question formulation is essential for examiners — our acquaintance tests guide covers how these events are structured in practice.

Timing values are expressed as sample numbers, not clock times. To convert to seconds, divide the sample number by the sampling rate. For example, at 30 Hz, an event starting at sample 1623 corresponds to approximately 54.1 seconds into the chart recording (1623 / 30 = 54.1). This sample-based approach provides exact, unambiguous temporal alignment between events and the physiological data matrix.

Each event records three timing markers: Begin (when the question presentation started), End (when the question presentation finished), and Answer (when the examinee responded). Instructional events like "X" (start) and "XX" (end) typically have no answer timestamp. Within the physiological data matrix, answer labels appear as the standardized strings "-----Yes", "------No", or "-----Ans" to mark the examinee's verbal response [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Core Channels and Extended Channels

The NCCA ASCII format supports five core physiological channels in fixed order, with up to five additional extended channels [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details:

UPneumo (Upper Pneumograph): Measures thoracic (chest) respiratory activity — breathing rate, depth, and patterns via circumference changes in the upper torso. Understanding respiratory suppression patterns is critical for interpreting this channel.

LPneumo (Lower Pneumograph): Records abdominal respiratory activity. Dual-pneumograph recording (upper + lower) has been the standard practice in modern polygraph testing. Lafayette introduced the first polygraph instrument that used dual pneumographs with their Model 76056 in 1972 [17]Verified Polygraph School — History of Polygraph Instrument
Confirms Lafayette Model 76056 (1972) was the first polygraph instrument using double pneumographs.

EDA1 (Electrodermal Activity): Measures skin conductance / galvanic skin response. The electrodermal channel is widely considered the most diagnostically powerful single channel in polygraph testing [18]Verified Appendix F: Computerized Scoring of Polygraph Data — National Research Council
Confirms the electrodermal channel is considered most diagnostic; describes differences between manufacturer EDA recording methods. It records sweat gland activity via finger electrodes.

Cardio1 (Cardiovascular): Records blood pressure and heart rate via sphygmomanometer cuff, tracking relative changes in cardiovascular activity throughout the chart. Baseline responses in this channel are crucial for accurate scoring.

Move1 (Movement Sensor): An activity sensor detecting body movement and physical countermeasure attempts. Placed on seat, under arms, or under feet. The column is filled with 9999.9 if no movement sensor was used [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Understanding suppression responses helps examiners interpret movement artifacts.

Up to five additional columns (channels 6–10) can be included for: PPG (photoplethysmograph), ECG, EMG, Voice, EDA2, plethysmography, temperature, pupil dilation, eye position, or electrooculogram [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Data Column Layout and Formatting

The physiological data matrix uses fixed-width, right-justified columns. Each physiological data column occupies 11 characters formatted as F11.1 (one decimal place) [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. The first three columns provide structural context: the sample number (starting at 1), the elapsed time in MM:SS.cc format (minutes:seconds.centiseconds), and the current event label (right-justified with leading hyphens, showing which question or event is active at that sample point).

All physiological data values must fall within the range 1.0 to 999999.9. If the raw analog-to-digital converter output falls outside this range, the manufacturer's export function must scale the data to fit within the allowed range before writing it to the ASCII file [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Missing data points — whether arising from channels sampled at different rates, sensor disconnections, or absent sensors — are written as the sentinel value -9.9. This unambiguously signals to any parsing software that no valid measurement exists at that sample point. This consistent sentinel value is one of the format's key strengths for automated data processing pipelines.

Axciton Systems

Axciton Systems was the first company to produce a commercially viable computerized polygraph system, with the initial system coming to market in 1990 [19]Verified History of Polygraph Digitization — ScienceDirect
Confirms first commercially viable computerized polygraph system came from Axciton in 1990. Bruce White of Axciton Systems began researching the transition from analog to digital polygraph in 1988 [20]Verified Polygraph School — Bruce White and Axciton
Confirms Bruce White began researching computerized polygraph at Axciton in 1988. Axciton has been exclusively focused on the advancement of computerized polygraph systems for over 25 years [21]Verified Axciton Systems Inc. Website
Confirms Axciton was the first company to produce a usable computerized polygraph system and has focused on computerized systems for 25+ years. For a detailed technical review, see our Axciton CPS system guide.

Axciton's current software (version 9.x) supports NCCA ASCII export. The Axciton system uses a 5-channel USB sensor box [22]Verified Axciton Sensor Box Packages
Confirms 5-channel USB sensor box configuration for Axciton systems and the $ symbol in NCCA ASCII file names. Axciton instruments use a hybrid of skin resistance and skin conductance for the electrodermal channel [18]Verified Appendix F: Computerized Scoring of Polygraph Data — National Research Council
Confirms the electrodermal channel is considered most diagnostic; describes differences between manufacturer EDA recording methods, which is an important consideration when comparing NCCA ASCII data across manufacturers.

Axciton's scoring capabilities include support for PolyScore, which was developed by Johns Hopkins University Applied Physics Laboratory [23]Verified A History of Polygraph Digitization — Peters
Confirms PolyScore was developed by Johns Hopkins University Applied Physics Laboratory for Axciton data, as well as their proprietary STAR scoring algorithm [24]Verified Lafayette Polygraph Manufacturers Overview
Overview of Lafayette instrument systems and capabilities.

Lafayette Instrument Company

Founded in 1947 by Max Wastl, Lafayette Instrument Company has been a cornerstone of the polygraph industry for over 75 years [25]Verified Our Story — Lafayette Instrument Company
Confirms Lafayette was established in 1947 by Max Wastl, and acquired Limestone Technologies in 2022. Lafayette produces the LX6, LX7, and formerly the LX5000 systems, and in 2022 acquired Limestone Technologies to further reinforce its commitment to the polygraph market [26]Verified Lafayette Instrument — Limestone Technologies Acquisition
Confirms Limestone Technologies Inc. was acquired in 2022 to reinforce Lafayette's polygraph market commitment.

Lafayette's newest software platform, LXEdge, is compatible with the LX6, LX7, and Paragon series hardware [27]Verified LXEdge Software — Lafayette Instrument
Confirms LXEdge is compatible with LX6, LX7, and Paragon series systems. LXEdge v1.3.0.38 was released on September 5, 2025, and included important updates such as added support for Paragon and ParagonX hardware, and fixes for NCCA export issues including correcting the EDA automatic trace refiltering during NCCA import [28]Verified LXEdge Version 1.3.0.38 Release Notes
Confirms LXEdge v1.3.0.38 released September 5, 2025; includes NCCA export fixes and Paragon support. Lafayette also maintains LXSoftware, their legacy platform, which continues to receive updates.

Lafayette uses the & symbol in NCCA ASCII file names and encodes the full examination name and date in the file identifier, providing rich context directly in the file name [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Limestone Technologies (ParagonX)

Limestone Technologies, now a subsidiary of Lafayette Instrument Company since August 2022 [15]Verified Limestone Technologies — Lafayette Instrument Company
Confirms Limestone became a subsidiary of Lafayette Instrument Company in August 2022, is known for its high-resolution data acquisition hardware. The ParagonX system operates at a native sampling rate of 625 samples per second per channel — the highest of any commercial polygraph instrument [16]Verified ParagonX Polygraph System — Limestone
Confirms native 625 samples per second per channel — highest sampling rate in any polygraph instrument. It features flush-mounted Lemo precision connectors for all nine inputs and dual-channel 32-bit resolution [16]Verified ParagonX Polygraph System — Limestone
Confirms native 625 samples per second per channel — highest sampling rate in any polygraph instrument. See our detailed overview of Lafayette and Limestone systems.

Limestone's Polygraph Pro Suite software provides NCCA ASCII export. Version 4.6.2.1 was released on August 21, 2024, and included important NCCA compliance updates — notably swapping data contained in EDA1 and EDA2 columns to match conventions, and modifying the NCCA export to conform to standards [29]Verified Polygraph Pro Suite v4.6.2.1 Release Notes
Confirms v4.6.2.1 released August 21, 2024 with NCCA export conformity updates including EDA column swap. The most recent version is v4.6.3.2, released November 5, 2024 [30]Verified Polygraph Pro Suite v4.6.3.2 Release Notes
Confirms v4.6.3.2 released November 5, 2024 with comprehensive NCCA export improvements.

Limestone uses the % symbol in NCCA ASCII file names and a year-based numbering scheme for examination identifiers [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Stoelting Company

Stoelting has been on the forefront of polygraph instrumentation design and manufacture since 1930 [31]Verified CPS Elite Polygraph Systems — Stoelting
Confirms Stoelting polygraph history since 1930, Elite as fourth-gen CPS with 360 Hz sampling and built-in LCD touchscreen. Their current flagship is the CPS Elite Polygraph System — the fourth generation Computerized Polygraph System — which features a built-in full-color LCD touchscreen display, the only polygraph unit with this capability [31]Verified CPS Elite Polygraph Systems — Stoelting
Confirms Stoelting polygraph history since 1930, Elite as fourth-gen CPS with 360 Hz sampling and built-in LCD touchscreen. The Elite's EDA and plethysmograph sensors sample at 360 samples per second [31]Verified CPS Elite Polygraph Systems — Stoelting
Confirms Stoelting polygraph history since 1930, Elite as fourth-gen CPS with 360 Hz sampling and built-in LCD touchscreen. For more details, see our Stoelting polygraph chair review.

Stoelting's CPSpro Fusion software provides the platform for chart recording, scoring, and export. Fusion can import data from Axciton, Lafayette, or Limestone systems as long as it was exported in pREFORMAT — a separate cross-platform format [11]Verified CPSpro Fusion Software — Stoelting
Confirms Fusion can import Axciton, Lafayette, or Limestone data exported in pREFORMAT. Fusion is loaded with features including a question editor, subject search, and validated scoring algorithms [11]Verified CPSpro Fusion Software — Stoelting
Confirms Fusion can import Axciton, Lafayette, or Limestone data exported in pREFORMAT.

Stoelting uses the # symbol in NCCA ASCII file names [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Older Stoelting-DOS systems use "X" as a fixed placeholder for examination type, while newer Windows versions use standard hexadecimal encoding.

Two Cross-Platform Formats in the Polygraph Industry

The polygraph field has two distinct cross-platform data formats: NCCA ASCII and pREFORMAT. While both enable data sharing between manufacturer platforms, they serve different purposes and have different adoption patterns.

NCCA ASCII is the APA-mandated standard, designed for research accessibility, quality control, and long-term data archival [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate. Its plain-text design makes it parseable by any programming language or text tool. Stoelting's CPSpro Fusion can import data from other manufacturers' systems when exported in pREFORMAT [11]Verified CPSpro Fusion Software — Stoelting
Confirms Fusion can import Axciton, Lafayette, or Limestone data exported in pREFORMAT, but NCCA ASCII remains the required standard for compliance with the APA Instrumentation Standard.

pREFORMAT is an older cross-platform format that predates the APA mandate and is primarily used for operational data exchange between software platforms. Understanding both formats is valuable for examiners working in multi-vendor environments, though NCCA ASCII should be the default choice for archival and research purposes.

Export Workflows by Platform

All four major polygraph software platforms provide NCCA ASCII export functionality. The exact menu location and workflow varies by manufacturer and software version, but the general process is consistent: select the chart(s) to export, choose the NCCA ASCII export option, and specify a destination folder.

For Lafayette LXEdge users, NCCA export has been refined through multiple software updates. The v1.3.0 release addressed issues where NCCA export files were sometimes created at a different data rate than expected, and resolved problems where question repeats were not being shown in the export [28]Verified LXEdge Version 1.3.0.38 Release Notes
Confirms LXEdge v1.3.0.38 released September 5, 2025; includes NCCA export fixes and Paragon support. It is important to always use the latest software version to ensure NCCA export compliance.

For Limestone Polygraph Pro Suite users, version 4.6.3.2 includes significant NCCA export improvements including correct EDA column ordering, proper filename generation, properly implemented event lists, and correct start/stop question markers ("X" and "XX") [30]Verified Polygraph Pro Suite v4.6.3.2 Release Notes
Confirms v4.6.3.2 released November 5, 2024 with comprehensive NCCA export improvements.

Examiners should maintain a workflow that includes NCCA ASCII export as part of their standard examination archival process. Proper documentation practices — including maintaining a complete test data sheet — complement the NCCA ASCII export by preserving the full examination context.

Working with Data in Analysis Tools

Because NCCA ASCII files are plain text with fixed-width columns, they can be parsed by virtually any data analysis tool. Python's pandas library, MATLAB's textscan function, R's read.fwf function, and even Microsoft Excel can import NCCA ASCII data with minimal preprocessing.

The key parsing considerations are: (1) skip the header lines to reach the physiological data matrix; (2) parse event timing separately as sample-number-based timestamps; (3) handle the -9.9 sentinel value for missing data; and (4) account for variable channel counts across files from different manufacturers.

For researchers working with concealed information test data, the standardized format enables sophisticated analyses. Modern approaches include the use of hierarchical Bayesian models for time-series physiological data [14]Verified Hierarchical Bayesian Modeling for Time Series Physiological Data During the CIT
Hierarchical Bayesian models applied to 167 participants' CIT data provided more accurate effect size estimates, multivariate hierarchical linear models for handling the multi-level structure of CIT data [32]Verified Applicability of Multivariate Hierarchical Linear Model to CIT Data
Foundational research relevant to statistical analysis of standardized polygraph data, and pretest screening methods to improve diagnostic accuracy [33]Verified Using Pretest Data to Screen Low-Reactivity Individuals in the CIT
Demonstrates pretest screening methods that improve CIT diagnostic accuracy — relevant to standardized data processing. The NCCA ASCII format's structured data output facilitates all of these analytical approaches.

Research on dispersion effects in physiological data analysis has shown that standard deviation substantially influences classification efficiency [34]Verified Dispersion Matters: Diagnostics and Control Data Computer Simulation in CIT Studies
Demonstrates that standard deviation substantially influences classification efficiency in physiological data analysis, underscoring the importance of clean, standardized data formats like NCCA ASCII for enabling accurate computational analysis.

Key Technical Parameters

File Format: Plain ASCII text, no tab characters, right-justified fixed-width columns [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

File Scope: One chart per file. A three-series, four-chart examination generates twelve NCCA ASCII files [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Maximum Output Sample Rate: 120 Hz (samples per second) [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details. Instruments with higher native rates must downsample for NCCA ASCII export.

Minimum Acquisition Rate: 25 samples per second, as mandated by the APA Instrumentation Standard [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate.

Core Channels: 5 — UPneumo, LPneumo, EDA1, Cardio1, Move1 [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Extended Channels: Up to 5 additional (channels 6–10) for PPG, ECG, EMG, Voice, EDA2, plethysmography, temperature, pupil dilation, eye position, or electrooculogram [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Data Value Range: 1.0 to 999999.9 (F11.1 format) [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Missing Data Sentinel: -9.9 [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Answer Labels: "-----Yes", "------No", or "-----Ans" [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Manufacturer Symbols: $ (Axciton), & (Lafayette), % (Limestone), # (Stoelting) [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Date Format: DDMMMYY (e.g., 12Aug19) [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Time Format: Military/24-hour notation [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

Native Sampling Rates by Manufacturer: Limestone ParagonX at 625 Hz/channel (highest) [16]Verified ParagonX Polygraph System — Limestone
Confirms native 625 samples per second per channel — highest sampling rate in any polygraph instrument, Stoelting Elite at 360 Hz/channel [31]Verified CPS Elite Polygraph Systems — Stoelting
Confirms Stoelting polygraph history since 1930, Elite as fourth-gen CPS with 360 Hz sampling and built-in LCD touchscreen, Lafayette LX systems at 360 Hz aggregate [35]Verified Lafayette LX System Hardware Manual — Data Sampling Rate
Confirms data sampling rate specifications for Lafayette LX systems.

What the APA Instrumentation Standard Requires

The APA Standard for Polygraph Instrumentation, approved August 25, 2023 and effective September 1, 2023, defines minimal design and functionality requirements for polygraph instrumentation [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate. Among its requirements, the standard mandates that each instrument shall support both importation and exportation of a standardized cross-platform data format — specifically the NCCA ASCII Standard [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate.

The standard also requires a minimum data acquisition rate of 25 samples per second [10]Verified APA Standard for Polygraph Instrumentation
Confirms approved August 25, 2023, effective September 1, 2023; mandates NCCA ASCII import/export; sets 25 Hz minimum acquisition rate, and specifies requirements for breathing sensors, cardiovascular sensors, electrodermal activity sensors, and movement sensors. All four major North American manufacturers — Axciton, Lafayette, Limestone, and Stoelting — currently support NCCA ASCII in their software [1]Verified Introduction to the NCCA ASCII Standard
Primary specification document for the NCCA ASCII format — confirms authorship by Kircher and Dollins, file structure, channel definitions, and all technical details.

For examiners and agencies, compliance means ensuring that: (1) your software is updated to a version that supports NCCA ASCII export and import; (2) exported files conform to the specification's column widths, data ranges, and formatting requirements; and (3) examination archives include NCCA ASCII exports alongside proprietary format files. Examiners should be aware that export control regulations also apply when shipping polygraph systems internationally.

Meeting manufacturer certification standards and maintaining proper testing environments are complementary requirements that work alongside NCCA ASCII compliance to ensure professional polygraph practice.