What does UDO stand for?

Undefinitized Delivery Order (MLEX)

Undetermined Origin - Medicine (AAMN)

Unit Deplaning Officer (SAUS)

United Display Organization - Switzerland (BUAC)

United States Fish and Wildlife Service, Billings, MT - OCLC symbol (OCLC)

Unwilling Drop-Out (SAUS)

User Defined Objects (SAUS)