XDAT - MajickTek/XFF-SPEC GitHub Wiki
The eXtensible Data format is not really a format on its own, but allows for embedding other types of data such as a data stream or a different file inside of this one. It is less complex than XSND, but in a sense is more powerful.
DATA
{
  id STRING
  compressed U8
  dataFormat U8
  dataLength U32
  data U8[dataLength]
}
That was easy, wasn't it? you probably are wondering what the "compressed" field is. That is used to determine if the data is ZLib-compressed or not! Cool, huh?
Well, we add to the FILE structure again to create this:
FILE
{
  header HEADER
  imageCount U16
  imageList IMAGE[imageCount]
  soundCount U16
  soundList SOUND[soundCount]
  dataCount U16
  dataList DATA[dataCount]
}
And that is that.