A programmatic identifier (ProgID) is a registry entry that can be associated with a CLSID. Like the CLSID, the ProgID identifies a class but with less precision because it is not guaranteed to be globally unique.
|CLSID||Associates a ProgID with a CLSID.|
|Insertable||Indicates that this class is insertable in OLE 2 containers.|
|Protocol||Indicates that this OLE 2 class is insertable in OLE 1 containers.|
|Shell||Provides Windows 3.1 shell printing and File Open information.|
You can use a ProgID in programming situations where it is not possible to use a CLSID. ProgIDs should not appear in the user interface. ProgIDs are not guaranteed to be unique, so they can be used only where name collisions are manageable.
The format of a ProgID is <Program>.<Component>.<Version>, separated by periods and with no spaces, as in Word.Document.6. The ProgID must comply with the following requirements:
- Have no more than 39 characters.
- Contain no punctuation (including underscores) except one or more periods.
- Not start with a digit.
- Be different from the class name of any OLE 1 application, including the OLE 1 version of the same application, if there is one.
The HKEY_LOCAL_MACHINE\SOFTWARE\Classes key corresponds to the HKEY_CLASSES_ROOT key, which was retained for compatibility with earlier versions of COM.