# EPOC Tools & Utilities Glossary

## Index U

Term | Topic | Meaning | See Also
UID | Makesis Guide | A UID is a globally unique 32-bit number used in a compound identifier to uniquely identify an object (see UIDs and Requesting UIDs from Symbian). When users refer to “UID” they often mean UID3, the identifier for a particular program. | UID1, UID2, UID3, compound identifier
UID1 | Makesis Guide | The first UID in a compound identifier; identifies the general type of an EPOC object and can be thought of as a system level identifier; for example executables, DLLs, and file stores are all distinguished by UID1 | UID
UID2 | Makesis Guide | The second UID in a compound identifier; distinguishes within a type(i.e. within a UID1); can be thought of as an interface identifier, for example static interface (shared library) and polymorphic interface (application or plug-in framework) DLLs are distinguished by UID2 | UID
UID3 | Makesis Guide | The third UID in a compound identifier; identifies a particular subtype and can be thought of as a project identifier (for example UID3 might be shared by all objects belonging to a given program, including library DLLs if any, framework DLLs, and all documents) | UID