XPT V8/V9 Specification

The XPT V8/V9 format extends the original V5 format with support for longer variable names and labels.

[!WARNING] XPT V8/V9 format is not accepted for FDA regulatory submissions. For regulatory submissions, use XPT V5 format only.

Key Differences from V5

Format Overview

XPT V8/V9 maintains the same basic structure as V5:

• 80-byte records for headers
• Big-endian byte order
• Fixed-width text fields (space-padded)

However, it differs in:

• Variable names: Extended from 8 to 32 characters
• Labels: Extended from 40 to 256 characters
• Numeric encoding: Uses IEEE 754 instead of IBM floating-point

Use Cases

V8/V9 format may be appropriate for:

• Internal data storage where longer names improve readability
• Non-regulatory data exchange between systems
• Archival purposes where V5 limitations are problematic
• Academic or research datasets not intended for regulatory submission

Regulatory Considerations

FDA Submissions

The FDA Data Standards Catalog explicitly requires XPT V5 format. Files in V8/V9 format will be rejected during technical validation.

CDISC Standards

CDISC standards (SDTM, ADaM) are designed around V5 limitations:

• Variable names: 8 characters maximum
• Labels: 40 characters maximum

Using V8/V9 format with CDISC data defeats the purpose of standardization.

Best Practice

If your data requires longer names or labels:

1. Use V5-compliant short names in the XPT file
2. Document full names in define.xml metadata
3. Use controlled terminology for consistency

Official Specification

SAS Technical Note: Record Layout of a SAS Version 8 or 9 Data Set in SAS Transport Format

Download PDF | View on SAS Support

xportrs Support

xportrs currently focuses on V5 format for regulatory compliance. V8/V9 support is not a priority as it cannot be used for regulatory submissions.

If you need V8/V9 support for non-regulatory purposes, please open an issue to discuss your use case.