Index: /trunk/doc/ipptools/filenames.txt
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--- /trunk/doc/ipptools/filenames.txt	(revision 8985)
+++ /trunk/doc/ipptools/filenames.txt	(revision 8985)
@@ -0,0 +1,25 @@
+Filename conventions for pipeline:
+
+Want to achieve something like: expId.state.classId.ext
+
+where expId is the unique exposure identifier;
+      state is the state of processing for that file;
+      classId is the class identifier, specifying a particular component of the exposure; and
+      ext is an extension indicating the type of file (e.g., fits).
+
+Constraint: classId cannot split components known only by the caller
+(pmFPAfile groups all of these into the {OUTPUT} variable).
+
+This constraint does not hinder us, since having the classId as the
+last element before the extension makes it simple to get all
+components of an exposure at a particular processing state.
+
+Some realisations:
+
+Input is typically:	expId.classId.ext
+Detrend processed:	expId.detproc.classId.ext
+Detrend residual:	expId.detresid.detId.iter.classId.ext
+Stacked detrend:	camera.detType.detId.iter.classId.ext
+Phase 1 processed:	expId.p1.classId.ext
+Phase 2 processed:	expId.p2.classId.ext
+Phase 3 processed:	expId.p3.classId.ext