Flag (1 byte) (LAPD)

Protocol: LAPD LAPD PCI

Field: flag

Length: 1 byte

Contents: start of frame / end of frame indicator.

The flag field is a synchronization pattern and always set to 01111110. If multiple frames are sent, a flag octet is used for both end of frame and start of frame indication.

In case that user data contain six or more bits set to one, a zero will be inserted after the fifth bit in order to avoid this bit chain being interpreted as flag octet.