I need help for to find PRO mts channels

[svhs]

hi all

MTS allowed up to a total of four audio channels. The fourth channel, PRO, was only used by the broadcasters.

i can't find any info about The fourth channel, PRO related to encoding and receiving broadcast equipment ....... a Link Feed ....modulator

AND mts spectrum like fm https://6904462f-a-62cb3a1a-s-sites....attredirects=0[IMG]FM Spectrum.pngtp://www.videokarma.org/attachment.php?attachmentid=202130&stc=1&d=1610607 448[/IMG]