Four octets marking the start of a subframe and giving its length.
Reading a capture
Scanned for rather than parsed. A receiver hunting for the next subframe looks for the signature byte and then checks the CRC, which is why both are here.
Subfields
EOF — Marks a delimiter that carries no MPDU — padding to the end.
MPDU Length — Length of the MPDU that follows, in octets.
CRC — An eight-bit check over the preceding two octets.
Delimiter Signature — A fixed byte, 0x4E, that a receiver scans for when hunting for the next subframe.