Blue? What is Rufus?

Here is a note on breed standard, and how it has changed:

1935: Colour: May be any shade of brindle – Black – White – Fawn or Red or any of these colors with white. Black and tan and liver not to be encouraged.
1948: Colour: Red, fawn, white, black or blue, or any of these colors with white. Any shade of brindle or any shade of brindle with white. Black-and-tan or liver colour not to be encouraged.
1987: Colour: Red, fawn, white, black or blue, or any one of these colors with white. Any shade of brindle or any shade of brindle with white. Black-and tan or liver colour highly undesirable.

Notes:
1) ‘Blue’ was not part of the original Standard. The old timers who ‘invented’ the Breed would probably have considered what we call ‘blue’ today actually as ‘liver’.
2) ‘Not to be encouraged’ was changed to ‘highly undesirable’ in 1987.