Exact PAR according to ITU-R BT.601
     | PAL       |  NTSC
4:3  | 1150/1053 | 38800/42651
16:9 | 4600/3159 | 155200/127953

Almost exact and commonly used ITU-PAR according to Jukka Aho’s well-known article. However he did not account for the fact that the top and bottom half-lines of the analog image are only half-height.
     | PAL     | NTSC
4:3  | 128/117 | 4320/4739
16:9 | 512/351 | 5760/4739

MPEG-4 PAR taken directly from the MPEG-4 standard documents.
Very similar to exact ITU figures and usually used for MPEG-4 encodings.
     | PAL   | NTSC
4:3  | 12/11 | 10/11
16:9 | 16/11 | 40/33

Generic PAR (i.e. ignoring ITU)
This leads to an exact 16:9 DAR for an uncropped 16:9 PAL frame.
     | PAL   | NTSC
4:3  | 16/15 | 8/9
16:9 | 64/45 | 32/27