Split STRING into substrings bounded by matches for SEPARATORS.
The beginning and end of STRING, and each match for SEPARATORS, are
splitting points. The substrings matching SEPARATORS are removed, and
the substrings between the splitting points are collected as a list,
which is returned.
If SEPARATORS is non-nil, it should be a regular expression matching text
which separates, but is not part of, the substrings. If nil it defaults to
`split-string-default-separators', normally "[ \f\t\n\r\v]+", and
OMIT-NULLS is forced to t.
If OMIT-NULLS is t, zero-length substrings are omitted from the list (so
that for the default value of SEPARATORS leading and trailing whitespace
are effectively trimmed). If nil, all zero-length substrings are retained,
which correctly parses CSV format, for example.
Note that the effect of `(split-string STRING)' is the same as
`(split-string STRING split-string-default-separators t)'. In the rare
case that you wish to retain zero-length substrings when splitting on
whitespace, use `(split-string STRING split-string-default-separators)'.
Modifies the match data; use `save-match-data' if necessary.