Spalding Phonogram Rules and Cue Words - PC\|MAC

(4) Two-letter State abbreviations. Two-letter State abbreviations may be used only on the envelope or in the address portion of the letter when using window envelopes. They should not be used in the body of the letter or in formal writing. (See Exhibit E of this Instruction and U.S. Government Correspondence Manual, Part 2, Chapter 5.) ................
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