--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/notes.txt	Sat Apr 01 12:57:31 2017 +0800
@@ -0,0 +1,37 @@
+You can't depend on 
+  <f si="..." t="shared"/>
+ That is, it's _true_, but you can have a table with shared formulae
+  that doesn't use it.  Compare M17:T28 (see below, uses shared) and
+  C17:J28 (mostly no shared) in sample4
+
+Looks like the result of a sweep-and-copy-{right,down} results in the
+_new_ cells covered showing as 'shared':
+
+         [ ][1][1][1][1]...
+         [2][2][2][2][2]...
+         [2][2][2][2][2]...
+         ...
+
+Presumably that one was right-then-down, down-then-right would give a
+slightly different pattern
+--------
+Thinking about a pipeline...
+ 1) convert all variable references into (verbose!) elts:
+     <!ELEMENT R EMPTY>
+     <!ATTLIST R
+        ac CDATA IMPLIED
+        rc CDATA IMPLIED
+        ar CDATA IMPLIED
+        rr CDATA IMPLIED>
+
+     where e.g. ac is 'absolute column'
+    'D6' --> <R rc='D' rr='6'/>
+     and
+    '$E5' --> <R ac='E' rr='5'/>
+--------
+Identifying dates is . . . tedious.  They will be ints or floats (?),
+with s="<int>", where the int is a 0-origin index into the list of
+<xf...numFmtId="<bin>".../>
+children of <cellXfs> in styles.xml, and bin is a built-in date format
+code, see 18.8.30 numFmt (Number Format) in ISO/IEC 29500-1:2016(E) ==
+C071691e.pdf