clarify new-style mask:

* AHFinderDirect doesn't setup bit fields
* string --> bitmask is done only once, at startup


git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinAnalysis/AHFinderDirect/trunk@1032 f88db872-0e4f-0410-b76b-b9085cfa78c5

1 files changed, 10 insertions, 0 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index d90dbf7..fdf0a89 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -879,6 +879,9 @@ excision.  This feature is controlled by the following parameteters:
 		We plan to eventually convert all Cactus excision
 		(and other uses of mask grid functions) to this scheme,
 		but at the moment not much code supports it.
+		Note that \thorn{AHFinderDirect} doesn't itself set
+		up any bit fields -- you must arrange for some other
+		thorn(s) to do this.
 	\end{description}
 
 \item[%%%
@@ -906,6 +909,13 @@ excision.  This feature is controlled by the following parameteters:
 	these parameters specify the mask grid function's name,
 	and the ``state'' names for ``inside'' and ``outside'' values
 	as registered with the \thorn{SpaceMask} thorn.
+
+	Note that at present \thorn{AHFinderDirect} only converts these
+	character strings into integer bit masks once, in its startup
+	routine.  This may change at some point to (re-)doing the
+	conversion at each horizon finding; this would work better if
+	the string names aren't registered until after \thorn{AHFinderDirect}'s
+	startup routine runs.
 \end{description}
 
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