The U nstructured O peration M arkup L anguage (UOML) OASIS Standard defines instructions to process documents, i.e., information that can be printed on paper.

Although expressed by XML, UOML is not a document format. It is an interface standard between application software and common platform software called DoCbase Management System (DCMS). Application software operates the document by issuing UOML instructions to DCMS, then DCMS implements operations defined by these instructions. This process is similar to database management system (DBMS), where UOML acts in a role similar to SQL.

UOML is a universally representative operating language for the abstract description of documents, with features including document organization, page description, information safety, index and search, content extraction, font management, plug-in mechanism, and script description, etc. UOML Part 1 only involves page layout and basic document organization; the other functions will be defined in UOML future parts.

UOML was approved as an OASIS Standard in 2008. UOML is vendor-neutral, document-format-neutral, application-neutral, platform-neutral and programming language neutral.