Exgencode.Pdu.sizeof_pdu

You're seeing just the function sizeof_pdu, go back to Exgencode.Pdu module for more information.
Link to this function

sizeof_pdu(pdu, version \\ nil, type \\ :bits)

Specs

Returns the size of the given version pdu. In case the version argument is not passed it returns full size (all fields defined within defpdu macro).

    Does not count subrecords size.