This memo describes a notion of programming language for expressing, from within a LISP system, string manipulation such as those performed in COMIT. The COMIT formalism has been extended in several ways: the patterns (the left-half constituents of COMIT terminology) can be variable names of the results of computation; predicates can be associated with these elementary patterns allowing more precise specifications of the segments they match; the names of elementary patterns themselves may be variable or the results if computation; it is no longer necessary to restrict the operations to a linear string of characters (or words) since elementary patterns can themselves match structures; etc. Similar generalizations exist for formats, i.e. what corresponds to the right-half of the COMIT rule.
