Everything after the SIGNAL field: a service field, the PSDU handed down by the MAC, and the tail and padding needed to fill whole OFDM symbols.
Reading a capture
This is where the coordinate system changes. Above here the units are microseconds of modulated symbols; the PSDU inside is counted in octets. The ratio between the two is the data rate.
Subfields
SERVICE field — Synchronises the receiver's descrambler and reserves the remaining bits.
Tail — Six bits returning the convolutional encoder to the zero state at the end of the frame.
Pad Bits — Enough zero bits to fill out the final OFDM symbol.