Serialization and header values

https://learninghub.kx.com/forums/topic/serialization-and-header-values

I'm currently looking at a pair of bytes which define a header in some code which is related to KDB serialization format.

The byte sequence is 0xFF, 0x01.

Does anyone know what this might mean?

This could be a red-herring, in that the code I am looking at might be a modified version of the KDB specification. So it is possible this byte sequence is not related to any KDB specification.