Manufacturer Part Numbers (MPN) often include variations that are non-functional.
Temperature rating of the component
Packaging information (e.g. reel, tray, tape)
RoHS / PbFree information
To capture every possible combination of part variation requires a large number of symbol aliases - this is to be avoided.
Where an MPN has options for such non-functional variations, these portions of the MPN should be replaced with a wildcard character (
Rule of thumb
A single symbol should be drawn for each footprint variation of an atomic part. Other variations (as listed above) do not require their own symbol alias.