Service Manuals, User Guides, Schematic Diagrams or docs for : IBM 370 DCF SH35-0050-2_Document_Composition_Facility_Generalized_Markup_Language_Implementation_Guide_Rel_3_Mar85
Most service manuals and schematics are PDF files, so You will need Adobre Acrobat Reader to view : Acrobat Download
Some of the files are DjVu format. Readers and resources available here : DjVu Resources
For the compressed files, most common are zip and rar. Please, extract files with Your favorite compression software ( WinZip, WinRAR ... ) before viewing.
If a document has multiple parts, You should download all, before extracting.
Good luck. Repair on Your own risk. Make sure You know what You are doing.