texmf
as the name of the root directory (folder) of the
hierarchies, and most distributions use that name for their ‘own’
trees. Files supplied as part of the distribution are put into the
distribution’s tree. The location of the distribution’s hierarchy is
system dependent, but on a Unix system it might be at
/usr/share/texmf or
/opt/texmf, or
a similar location, but in each case the TeX files will be in the
tree starting at the /texmf subdirectory.
There may be more than one ‘local’ hierarchy in which additional files
can be stored. In the extreme an installation can have a local
hierarchy and each user can also have an individual local hierarchy.
The location of any local hierarchy is not only system dependent but
also user dependent. Again, though, all files should be put under a
local /texmf directory.
The TDS itself is published as the output of a TUG
Technical Working Group. You may browse an
on-line version of the standard, and
copies in several other formats (including source) are available on
CTAN.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=tds