# Class Pxp_reader.lookup_public_id_as_file

    class lookup_public_id_as_file : ?fixenc:Pxp_types.encoding -> (string * string) list -> resolver

Makes a resolver for `PUBLIC` identifiers. The list (catalog) argument specifies pairs `(pubid, filename)` mapping `PUBLIC` identifiers to filenames. The filenames must already be encoded in the character set the system uses for filenames.

There is a restriction of this catalog class: After a `PUBLIC` entity has been opened, it is not possible to refer to sub entities by relative `SYSTEM` names, even if the `PUBLIC` name is accompanied by a resovable system name like in `Public(pubid,sysid)`. Workaround: Use `lookup_id` instead, and put the complete `Public(pubid,sysid)` ID's into the catalog.

`fixenc`: Overrides the encoding of the file contents. By default, the standard rule is applied to find out the encoding of the file.