Use a groupsign when the addition of a prefix or the formation of an unhyphenated compound word provides an opportunity to use a groupsign not used in the original word, even if this alters the usual braille form of the original word. However, do not use the groupsign if its use would hinder the recognition or pronunciation of the word.

With the exceptions of 10.11.3 and 10.11.4 above, in general use a groupsign which bridges a prefix and the remainder of a word unless its use would hinder the recognition or pronunciation of the word. In particular, use the groupsigns for "ed", "en", "er", "of" and "st".

Do not use the lower groupsign for "ea" when the letters "ea" bridge a prefix and the remainder of the word.

Use the lower groupsign for "be", "con" or "dis" when the letters it represents form the first syllable of a word.

Do not use the strong groupsigns for "ch", "gh", "sh", "th", or "wh" or the strong contraction for "the" when the "h" is aspirated.

Do not use a groupsign which would bridge the words which make up an unhyphenated compound word. 

When transcribing dates, time, coinage, ordinal numbers, postal codes or telephone numbers: follow print punctuation and order of symbols.

Refer to: Guidelines for Technical Material, Part 2, for more examples.

Do not use the final groupsign or wordsign in a sequence that would otherwise consist wholly of lower signs. For the purposes of this rule, any type of quotation mark which may be present is considered to have only lower dots. When a capitals indicator or a capitals terminator is present, it is disregarded in determining whether to use a lower wordsign.

The spaced numeric indicator allows one or more spaces to intervene between the numeric prefix and the root that would normally follow immediately to form a digit or a decimal point or comma.

Do not use a groupsign if its use would seriously distort the pronunciation or hinder the recognition of the word.