Specifies schema for retrieval - Справочник: PHP5.4

void yaz_schema ( resource $id , string $schema )

yaz_schema() specifies the schema for retrieval.

This function should be called before yaz_search() or yaz_present().

id: The connection resource returned by yaz_connect().
schema: Must be specified as an OID (Object Identifier) in a raw dot-notation (like 1.2.840.10003.13.4) or as one of the known registered schemas: GILS-schema, Holdings, Zthes, ...

Эта функция не возвращает значения после выполнения.