MTEF selector -126 (0x82) causes parse failure

[eshreyareddy]

MTEF Selector '-126' (0x82) Causes Parse Failure

Issue

Getting parse errors when converting some MTEF OLE objects to MathML. Both mathtype_to_mathml and mathtype_to_mathml_plus gems fail on selector value -126 (0x82 hex).

Error Messages

mathtype_to_mathml_plus (v0.0.15):

undefined method 'default_namespace=' for nil

mathtype_to_mathml (v0.0.7):

selection '-126' does not exist in :choices for obj.equation[0].payload

Reproduction

Extract MathType OLE object from DOCX (word/embeddings/oleObject*.bin) and attempt conversion:

require 'mathtype_to_mathml_plus'
MathTypeToMathMLPlus::Converter.new('oleObjectXXX.bin').convert

The error occurs consistently on equations with selector value -126.

Note: I have sample .bin files that reproduce this, but they're extracted from internal documents.

Analysis

• Selector -126 (0x82 unsigned) is outside documented MTEF v5 spec range
• Likely a MathType 6/7 extension
• All equations with this selector fail consistently

Expected

Parser should handle selector 0x82 or fail gracefully with a clear message.

Actual

Hard failure with no MathML output.

Question

What does selector 0x82 represent? Can support be added for this construct?

Workaround

Currently preserving failed equations as images instead of MathML.

Thanks!

[gimsieke]

Thanks for reporting this. Unfortunately, I doubt that there is anything that we can do about it since we currently don’t have a maintainer for this MTEF extension.

[mkraetke]

@eshreyareddy would you please provide a minimal sample of the document that caused this issue?