Star includes a pattern matcher based on the algorithm
presented by Martin Richards in:

"A Compact Function for Regular Expression Pattern Matching", 
Software-Practice and Experience, Vol. 9, 527-534 (1979)

Several changes have been made to the original source which has been
written in BCPL:

'/'	is replaced by	'!'		(to allow UNIX filenames)
'(',')' are replaced by	'{', '}'
'\''	is replaced by	'\\'		(UNIX compatible quote)

Character classes have been added to allow "[<character list>]"
to be used.
Start of line '^' and end of line '$' have been added.

A description is available in the man page for the match program.
It may be found in man/man1/match.1