Based on Cave Map Language, which is a text-based system for writing down just about all the data about a cave that can be written down. It is free format and any caver can understand the data just by inspecting it. This is because CML accepts all the ways in which we normally write data in our survey books. It has its own memory manager so it is not limited in size or number of files it can process or the complexity of the cave. One or more text files.
Connectivity is derived from semantics so the data can appear in any sequence.
People experienced in emacs could customize this. Feet and inches and metric are supported. This can be used to attach passage attribute information to stations and party information to trips. Least squares, based on the CMAP algorithms. Postscript output produces quads.