In IMS data, the <sourcedid> field represents the persistent ID code for a person as used in the source system. The <userid> field is a separate field which should contain the ID code used by the user when logging in. In many cases these two codes may be the same - but not always.

Some student information systems fail to output the <userid> field. If this is the case, you should enable this setting to allow for using the <sourcedid> as the Moodle user ID. Otherwise, leave this setting disabled.