strfind(<sString>, <sPattern> [, <iInit> [, <bPlain>]])
Description (from LUA 4 Manual: 6.2 String Manipulation
"Looks for the first match of <sPattern> in <sString>. If it finds one, then strfind returns the indices
[sic: e.g., positions] of <sString> where this occurrence starts and ends; otherwise, it returns nil. If the pattern specifies captures (see gsub below), the captured strings are returned as extra results. A third, optional numerical argument <iInit> specifies where to start the search; its default value is 1, and may be negative. A value of 1 as a fourth, optional argument <bPlain> turns off the pattern matching facilities, so the function does a plain 'find substring' operation, with no characters in pattern being considered 'magic'. Note that if plain is given, then <iInit> must be given too."
<sString>: the string to search in.
<sPattern>: the pattern to search for.
<iInit>: the position to start searching at.
<bPlain>: specifies that a 'plain' search should be done (i.e., one in which there are no 'magic' characters).