One way to make the FITS format as flexible as HDS is by introducing some system for the linking together of data extension. This can be done by adding extra KEYWORDS into each data block that define a tree-like structure within the existing linear arrangement.
Like many such FITS extensions, whilst useful, there would be little chance of having the proposal adopted by OGIP, and thus any use made of this system by ASTERIX might limit its use to ASTERIX created FITS files.
The following extra keywords are proposed;
Block names are those defined by the EXTNAME keyword.
If the reading application can parse these extra keywords then the implied hierarchical structure can be unfolded, otherwise the existing linear structure will be unaffected. Code to implement this scheme is available in /lsoft1/asterix/work/rb/adi/newsrc.