A basic understanding of how Part Numbers are setup:
The item number in the Vision program begins with the Line Code the part number following that line code can be the MPN (manufactures part number) or a User Part number.
MPN: Most manufactures follow Nomenclature rules - this simply means most part numbers are not just random numbers they have a map and each character in that part number means something and parts in the same group or family will share several of the same numbers.  You can find the different rules for each manufacture and note it in the default line code item for future reference.  
Some parts are simply setup as what can be referred to as Serial Parts meaning that number is unique to that item and does not share any mapping with other items even similar items (not to be confused with Serial Numbers on serialized parts)
User Part Number: a part number created by the seller of the part not the maker of the part - quite often your vendors will use their own part number, to avoid confusion you can set these numbers up in the Alternate Supplier area for ordering on PO's only and not have to create the same part multiple times in your inventory just because a vendor uses a different number.

• For consistency it is best to use the MPN when available.
• There is not a space between the Line Code and the Part Number.
• Spaces in part numbers should only be used if the MPN is setup that way for sizing or other specific needs, use spaces with caution.
• Even spaces are seen as a character so would have to be used in searching.
• Special Characters should only be used if the MPN is setup that way for sizing or other specific needs, use special characters with caution.