pulse in the analogue field sync. Digital formats use a single-bit in their Timing Reference Sequence as the "Field" flag. Field flag bit F=0 marks the first field of each frame. F=1 Marks the second field. PsF Line Numbers In Progressive segmented frame (PsF), which is a way of sending a progressively scanned picture over an interlaced system, each alternate field will contain the odd and even lines of the original progressive scan. But once it is being carried as an interlaced picture the lines are numbered in the order they are being sent as with any 'normal' interlaced system. See also Color framing External links All About Video Fields Interlace, Interleave, and Field Dominance Film and video technology Video signal Film and video terminology