Have anyone ever specified the Material to be used during the welding process of sheet metal parts? My drawing specified the base material to be welded (Similar material) for all parts.

I know we specify the weld type, Size, Spacing, grinding after weld etc. but never the welding material. I've always assumed that the material used for the welding will always be the same material as the base parts. If anyone can point me where the material to be used is specified in any standard, that would be really appreciated. Thanks in advance for any help.