A UID is a globally unique identifier consisting of a 32-bit number.
UIDs are used throughout the Symbian platform to enable various kinds of file identification and association. Because UIDs are fundamental to the Symbian platform, it is important that they are used correctly when developing programs.
UIDs are split into 2 ranges; protected and unprotected. The protected range consists in UID values less than or equal to 0x7FFFFFFF, and is only intended for use with signed applications (or those pre-installed in ROM). If you are developing an application that you intend to Symbian Sign, you should use UIDs from the protected range.
To ensure uniqueness, it is essential that UIDs are properly allocated. Uniqueness is guaranteed by allocating UIDs centrally from a database managed by Symbian Signed at https://www.symbiansigned.com. To obtain a UID, first register with Symbian Signed. Once you have registered and logged in, click on "UIDs" and then "Request" on the left navigation bar.