VX/FDL - File Description Language Routines

Overview

VX/FDL is an implementation of VMS / OpenVMS File Description Language (FDL) for Linux and Windows. It enables the creation, analysis, and management of RMS files with identical structure and behavior to their VMS counterparts.

With VX/RT, users can:

• Import VMS / OpenVMS FDL files

• Recreate RMS files with all supported organizations and formats

• Use VX/DCL commands for FDL file management

• Leverage a call-compatible library for FDL$() API functions

VX/FDL Features

Feature	Description
Full FDL Support	Handles all Indexed, Relative, and Sequential RMS file organizations.
Record Format Compatibility	Supports Sequential and Fixed record formats, ensuring 1:1 mapping with VMS files.
VX/DCL Integration	Includes support for `CREATE/FDL` and `ANALYZE/FDL` commands.
Call-Compatible API	Provides a full implementation of the `FDL$()` API library.
VMS FDL Import & Conversion	Allows importing and recreating VMS / OpenVMS FDL files for VX/RMS.

Creating a VX/RMS File from a VMS / OpenVMS FDL

To create an RMS file from an FDL specification, use:

CREATE/FDL=fdl-filespec [filespec]

This command reads the specified FDL file and generates a matching RMS file on Linux or Windows.

Example:

CREATE/FDL=customer.fdl customer.dat

This will create customer.dat with the structure defined in customer.fdl.

Creating a VMS / OpenVMS FDL from a VX/RMS File

To generate an FDL file from an existing RMS file, use:

ANALYZE/FDL/RMS_FILE customer.dat

Example:

ANALYZE/FDL/RMS_FILE customer.dat

This will produce customer.fdl, which can be used to recreate the RMS file structure.

VX/DCL Support for FDL Management

VX/DCL includes the following VMS FDL commands:
‍

VX/DCL Command	Description
CREATE/FDL	Creates an RMS file from an FDL specification.
ANALYZE/FDL	Extracts an FDL specification from an existing RMS file.

VX/FDL$() Call-Compatible API for x86 Intel Linux

VX/FDL provides a call-compatible library that allows developers to integrate FDL functionality into their applications.

Supported API calls include:
‍

API Function	Description
FDL$CREATE	Creates an RMS file based on an FDL specification.
FDL$GENERATE	Generates an FDL file from an RMS file.
FDL$PARSE	Parses an existing FDL file.
FDL$RELEASE	Releases FDL structures from memory.

Why Use VX/FDL?

✅ Fully Compatible with VMS / OpenVMS FDL

✅ Allows seamless migration of RMS files to Linux & Windows

✅ Provides identical structure and behavior for RMS data

✅ Includes VX/DCL support for automation

✅ Supports both command-line and API-based workflows

VX/FDL ensures that legacy RMS data remains accessible, structured, and functional on modern platforms, providing a seamless migration path for OpenVMS applications.