Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

XPT (SAS Transport) Format

XPT is the FDA-standard format for regulatory data submissions.

Overview

The SAS Transport Format (XPT) is:

  • Required by FDA for electronic submissions
  • A platform-independent binary format
  • Compatible with SAS and other tools
  • The de facto standard for clinical data exchange

XPT Versions

Trial Submission Studio supports two XPT versions:

XPT Version 5 (FDA Standard)

CharacteristicLimit
Variable name length8 characters
Variable label length40 characters
Record length8,192 bytes
Numeric precision8 bytes (IEEE)

Use for: FDA submissions, regulatory requirements

XPT Version 8 (Extended)

CharacteristicLimit
Variable name length32 characters
Variable label length256 characters
Record length131,072 bytes
Numeric precision8 bytes (IEEE)

Use for: Internal use, longer names needed

File Structure

Header Records

XPT files contain metadata headers:

  • Library header (first record)
  • Member header (dataset info)
  • Namestr records (variable definitions)

Data Records

  • Fixed-width records
  • Packed binary format
  • IEEE floating-point numbers

Creating XPT Files

Export Steps

  1. Complete data mapping
  2. Run validation
  3. Click Export → XPT
  4. Select version (V5 or V8)
  5. Choose output location
  6. Click Save

Export Options

OptionDescription
VersionV5 (default) or V8
Sort by keysOrder records by key variables
Include metadataDataset label, variable labels

XPT Constraints

Variable Names

V5 Requirements:

  • Maximum 8 characters
  • Start with letter or underscore
  • Alphanumeric and underscore only
  • Uppercase recommended

V8 Requirements:

  • Maximum 32 characters
  • Same character restrictions

Variable Labels

V5: 40 characters max V8: 256 characters max

Data Values

Character variables:

  • V5: Max 200 bytes per value
  • Trailing spaces trimmed
  • Missing = blank

Numeric variables:

  • 8-byte IEEE format
  • 28 SAS missing value codes supported (.A through .Z, ._)
  • Precision: ~15 significant digits

Numeric Precision

IEEE to SAS Conversion

Trial Submission Studio handles:

  • IEEE 754 double precision
  • SAS missing value encoding
  • Proper byte ordering

Missing Values

SAS/XPT supports 28 missing value codes:

CodeMeaning
.Standard missing
.A - .ZSpecial missing A-Z
._Underscore missing

Validation Before Export

Automatic Checks

  • Variable name lengths
  • Label lengths
  • Data type compatibility
  • Value length limits

Common Issues

IssueSolution
Name too longUse V8 or rename
Label truncatedShorten label
Value too longTruncate or split

Post-Export Verification

  1. Check file size - Matches expected data volume
  2. Open in viewer - Verify structure
  3. Validate with external tools - Pinnacle 21, SAS
  4. Compare row counts - Match source data

External Validation

Consider validating with:

  • Pinnacle 21 Community (free)
  • SAS Universal Viewer
  • Other XPT readers

FDA Submission Requirements

Required Format

  • XPT Version 5 for FDA submissions
  • Define-XML 2.1 for metadata
  • Appropriate file naming (lowercase domain codes)

File Naming Convention

  • dm.xpt - Demographics
  • ae.xpt - Adverse Events
  • vs.xpt - Vital Signs
  • (lowercase domain abbreviation)

Dataset Limits

ConstraintLimit
File size5 GB (practical limit)
Variables per datasetNo formal limit
Records per datasetNo formal limit

Technical Details

Byte Order

  • XPT uses big-endian byte order
  • Trial Submission Studio handles conversion automatically

Character Encoding

  • ASCII-compatible
  • Extended ASCII for special characters
  • UTF-8 source data converted appropriately

Record Blocking

  • 80-byte logical records
  • Blocked for efficiency
  • Headers use fixed-format records

Next Steps