All (most?) hieroglyphic texts are in fact edition of source texts. As such the editors of many texts annotate the source documents to deal with discrepancies and damaged parts of the source texts.
LPDH defines a few types of syntax elements, known as parentheses to express differences between the edited version of a text and its source.
[[ and ]] (rendered as [ and ])
express signs removed by the scribe.
[{ and }] (rendered as { and })
express signs removed by the editor.
[& and &] (rendered as < and >)
express signs added by the editor.
[" and "] (rendered as [| and |])
express signs that once were visible in the source document but are no longer
visible.
Full space quadrats (empty quadrats) are represented by ..
Half space quadrats (empty quadrats at half-width) are represented by .
Space quadrats are just like other regular glyphs (albeit empty ones): they can be combined with operators to form complex quadrats and modifiers and shading can be applied to them.
Red dots are represented by RD
Black dots are represented by BD
Like other glyphs, they can be combined with operators to form complex quadrats and modifiers and shading can be applied to them.