4.7 Empty Cell terminology and its uses in Part 3 Schema and Part 4 OpenFormula

Original proposal

The terminology "Empty Cell" in the specification creates semantic confusion because we also find the empty string of type Text. The term makes parts of the specification ambigious and unintuitive to read, for instance (cmp. OFFICE-3764) in Part 4: 4.11.8 "For =, if the value is empty it matches empty cells."

The definition in Part 4: 4.7 reads "Empty Cell - An empty cell is neither zero nor the empty string, and an empty cell can be distinguished from cells containing values (including zero and the empty string). An empty cell is not the same as an Error, in particular, it is distinguishable from the Error #N/A (not available)."

From OFFICE-3786 (references updated to ODF 1.4):

Part 3: 19.688 table:operator has no definition for empty/non-empty cell -

Whether we re-define empty cell in Part 4 or not, all of ODF should use the same definition. Need to make a reference to definition of empty cell in Part 4.

From OFFICE-3787 :

6.3.5 Conversion to Number: (last bullet item, end of paragraph) - "If the cell is empty (blank), use 0 (zero) as the value. Evaluators may choose to convert references to Text in a different manner than they handle converting embedded Text to a Number."

6.3.14 Conversion to Text (last bullet item): "Reference: perform conversion to scalar. If the referenced cell is empty, treat as an empty string (a text value with length 0). Then perform as above."

6.3.15 Conversion to DateParam (last bullet item): "Reference: perform conversion to scalar, then perform as above. If the cell is empty, return 0."

6.3.16 Conversion to TimeParam (last bullet item): "Reference: perform conversion to scalar, then perform as above. If the cell is empty, return 0."

This happens in 6.13.8 COUNTBLANK and 6.13.14 ISBLANK but they are too intertwined to fix separately (and they have other issues. I will open a separate JIRA issue on them.

Reference, convert cell value to Number. Empty cell returns the value 0. After conversion or empty cell value return, perform conversion for Number, 6.3.14.