I've noticed that a lot of people, here and elsewhere on the 'net, use the colon and plus sign interchangeably to indicate dilutions. For example,

Rodinal 1:50 / Rodinal 1+50

Isn't there a difference? (albeit a very small one).

1:50 1+49
1:25 1+24
1:2 1+1
1:1 1

I don't think it matters whether you dilute 1+50 instead of 1+49, but the last two lines of the table above could be really confusing. Technically, 1:1 is a stock dilution (undiluted), but if you use + and : without noting the difference, you end up with a 1+1 (that's 1:2 using the colon) dilution. Quite a difference.

Maybe I'm just wrong about all this, so please correct me if I am. I just wanted to know if there's a consensus among you fine people. How does one indicate dilutions in a standardized and non-confusing way?