Question about the causal state

[Williams, Pat]

I'd appreciate a clear explanation of  what's meant when the term
"causal" is used.  For example, I've been reading the treatment of
Mandukya Upanishad by Swami Nikhilananda, in which he intersperses
material from the sruti along with commentary from Shankara, Gaudapada,
and himself.  The deep sleep state is referred to as "causal" because it
precedes the other two states.  This makes some sense to me, although I
suspect there's some additional meaning to "causal" in this context.
But the term is also used to refer to other "states,", levels," etc.
When it is used thusly, exactly what does it mean?  Why is "causal" an
apt term in these contexts?

Thanks.
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Patrick S. Williams
Department of Social Sciences
University of Houston-Downtown
Houston, TX  77002
713-221-8982