tasm - Assembly, the meaning behind the colon ":" -

i'm new assembly , i'm reading guide express things ax:bx, ds:dx, ss:sp.

i'll use 1 of above in example book "mastering turbo assembly" page 85.

notice logical address in ss:sp points byte below last byte in stack.

what meaning of : notation?

kind regards.

those memory addresses expressed in segment:offset scheme. see e.g. http://thestarman.pcministry.com/asm/debug/segments.html