The NDF (Extensible N-Dimensional Data Format) data access library (SUN/33) provides a programming interface and a data model for astronomical applications software. It is based on a flexible underlying data format HDS (SUN/92) and a set of conventions for structuring data within HDS.
This document describes facilities for extending the range of data formats accessible via the NDF library, to include any arbitrary ``foreign'' format for which a conversion utility can be defined. This gives NDF-based applications access to a potentially wide range of data formatting possibilities, including data compression.
The intended readership of this document includes: