для бинари в тайп спеке можно это:
binary() —- A blob of binary data.
<<_:Integer>> —- A binary of a known size, where Integer is the size.
<<_:_*Integer>> —— A binary that has a given unit size, but of unspecified length.
<<_:Integer, _:_*OtherInteger>> —- A mix of both previous forms to specify that a binary can have a minimum length.