relative mode interacting wierdly with polyphony

[Ted Walther]

I am learning lilypond by transcribing Blake's "Jerusalem" into Lilypond
format.

In relative mode, the definition of , and ' depends on the "last" note.
Because of the behavior I will describe below, I'd appreciate a
clarification of how "the last" note is defined.

I have two different staffs.  Each staff usually has two voices going at
once.  I've been doing it a bar at a time, and for each bar, putting in
a << { } // { } >> section.  Now that I am 10 bars in, I'm noticing that
the previous five bars are getting messed up, to varying degrees, as I
add each new bar.  It is as if the definition of the "last" note that
the , and ' octavation marks apply to is getting changed on the fly
based on the new input.

Is my procedure wrong?  Should I be letting the voices run all the way
to the end instead of starting and stopping them at each bar?

When I have two voices on the same staff, if the passage of time is
marked by a note in one voice, will a rest in another voice in the same
staff be made invisible?  Is there a way to make it so?

You can see what I currently have here:

    http://reactor-core.org/~djw/jerusalem.ly

Ted

--
          It's not true unless it makes you laugh,                           
     but you don't understand it until it makes you weep.

Eukleia: Ted Walther
Address: 5690 Pioneer Ave, Burnaby, BC  V5H2X6 (Canada)
Contact: 604-430-4973