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A mathematical glyph assembly constructs an extended mathematical shape from positioned glyph parts. An OpenType MATH table records each part's full advance and glyph connectors; extender parts may repeat, with overlaps joining neighbouring pieces.^[ref]

For an invented vertical assembly, take bottom, middle and top parts with advances 500, 400 and 500 font units. Give each joining connector length 150 and require at least 80 font units of overlap. Choosing overlaps of 100 is then allowed. Starting at zero puts the parts at offsets 0, 400 and 700, giving total extentRepeating the middle part once, with another 100-unit overlap, adds $400-100=300$ and gives extent 1500. These are construction measurements along the growth direction, not a claim about a particular font's ink bounds. Positioning the assembled shape relative to the text baseline remains a separate layout choice.