PDP-8/A bus levels?

I am trying to figure out the voltages on my PDP-8/A (Omnibus) logic lines. DEC's documentation, as usual, is confusing at best on this (and other) subjects, and sometimes apparently self-contradictory... DEC used suffixes -L and -H to mean active-low and -high respectively (that is, a logical assertion). They also say when interfacing to the Omnibus that standard TTL levels are used. But elsewhere in the manual it says Logic 1 levels are near 0 volts and logic 0 is near 5 volts! So does this statement apply only to the bus signals that are already active-low? Am I correct or not in interpreting, for example, an address line named "MA 11 L" to be a logic 1/true/asserted when 0-0.8 volts and logic 0/false when 2.0+ volts (TTL levels)? thanks for any assistance. -Charles