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Re: 100% and 75% bars

Ladies and Gentlemen,

Am I alone in my understanding of colour bar nomenclature (from a European

As a cub engineer 15 years ago at the BBC, we were taught a four digit
representation for bars - a:b:c:d.

    a is the "on" value for a _non-coloured_, ie white bar
    b is the "off" value for a _non-coloured_, ie black bar
    c is the "on" value for a _coloured_ bar
    d is the "off" value for a _coloured_ bar

So, I would understand :-

    100:0:100:0 as 100% bars, where each RGB value is either fully on or fully
    100:0:75:0 would be 75% bars, where RGB numbers are at 75% of max in all
except the white bar
    100:0:100:25 I vaguely remember as EBU, or 95%, bars (for reasons that I
don't recall)
    100:7.5:75:7.5 (or is it 75:7.5:75:7.5 ?) I think was the number set for
NTSC, but its a long time ago now

Is this nomenclature in use anywhere else?

Best Regards,

Simon Aglionby