FourCC
identifier for a file type
FourCC (Four Character Code, 4CC) is identifier of length of four bytes used to identify type of data format (e.g. video codec used in AVI multimedia container).
The same video format can be (in dependency to used codec) denoted by several different FourCC codes. Even there is no exception to the rule to use more FourCC codes for that format by same codec. For example, some different DivX codec versions denote MPEG-4 ASP format by DIVX and DX50 codes. Therefore, selection of this code depends on used codec and thus on used multimedia framework.
Other websites
change- FourCC.org – FourCC codes for video codecs and uncompressed formats