class lookup_system_id_as_file :Looks up resolvers for URL identifiers: The catalog argument specifies pairs?fixenc:Pxp_types.encoding -> (string * string) list ->resolver
(url, filename) mapping URL's to filenames. The
filenames must already be encoded in the character set the system uses
for filenames.
Note: URL's are simply compared literally, without making
relative IDs absolute. See norm_system_id below for improving this.
fixenc: Overrides the encoding of the file contents. By default, the
standard rule is applied to find out the encoding of the file.
