View source for TAP file format

It's a viable format and is easy to put together. Several tools support output to tap.

For BASIC portions of tap files, it's most common to use a tool like bas2tap that will convert an ASCII text file containing a basic program to tap fragment.

The next has dot commands like '''tapein''' to mount a tap and from BASIC you indicate you want to redirect LOAD, SAVE to the tap file with '''LOAD "t:"'''. '''lstap''' will list the contents and position of each tap fragment in the tap file. '''extract''' can be used to pull out individual pieces of a tap file.  In longer term there will probably be another dot command that can extract an entire tap file into individual files.

The esx api has a lot of support for tap files too, allowing you to seek in them, etc.