In the examples of the General Fraction Indicator in Technical Materials (6.4) there are are examples that shown the grade 1 indicator being used as a passage, symbol and word. Could you please explain the criteria that is being used here? There seems not to be an explanation in regards to the fractions.
Really this is a UEB and not a Nemeth question, and UEB is not my particular field of expertise.
Still, I can tell you the following:
The use of a UEB grade 1 symbol, word, or passage indicator depends on the symbols-sequence(s) that is/are being put into grade 1.
The numeric indicator sets grade 1 mode.
When a numeric indicator, which sets grade 1 mode, is preceded by material, a grade 1 indicator may be needed for that preceding material. The "size" of grade 1 indicator chosen (symbol, word, or passage) depends on the extent of the preceding material.
For further information, please re-post this question in the UEB Ask an Expert forum.