The "Guidance for Transcription Using the Nemeth Code within UEB Contexts" provides the "single-word switch indicator" for instances in which A SINGLE WORD appears between two math expressions. A word that is preceded by the single-word switch indicator should be transcribed according to the Rules of Unified English Braille, which may include contractions.
In the "Guidance for Transcription Using the Nemeth Code within UEB Contexts," please see #4 under Basic Guidance on When to Switch as well as the examples on page 4.
Again, the single-word switch indicator allows ONE non-mathematical word to appear between pieces of technical material within Nemeth switch indicators, and that one non-mathematical word could include contractions.
Any word that is part of a mathematical expression cannot include contractions. Any series of two or more non-mathematical/narrative words that occurs between mathematical expressions must be preceded by a Nemeth Code terminator and followed by an Opening Nemeth Code indicator.
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