As a general rule contractions are used in abbreviations that represent a single word regardless of whether or not they could have been used in the complete word. Examples:
|St. Paul, Minn.||Little Rock, Ark.|
|Prof. Smith||first ed. [edition]||Ted Mead, Ed. [editor]|
|Phys. Ed. Dept.||ch. 7, pg. 3|
• Note: When the abbreviation for chapter (ch) is followed by a period, the ch contraction is used. The contraction cannot be used if there is no period because it would be read as child.
Do not use the in contraction in the abbreviation for inch (in) or inches (ins). [VIII.31.a] Examples:
|8 ins.||3ft, 6in||8-in. dia.|
Do not use contractions for two-letter postal abbreviations such as AR [Arkansas] and IN [Indiana].
Do not use the contractions for be, con, or dis in an abbreviation if they do not constitute
the first syllable in the complete word. [XIII.43.a]
Examples: Belg. [Belgium] (Con)n. [Connecticut]
Do not use the contractions for be, con, or dis if they comprise the entire abbreviation.
Examples: Dis. [District] Be [beryllium] Con. [Consolidated]
Do not use a one-cell, whole-word contraction for an abbreviation.
Examples: Can [Canada] IT [Italy] do [ditto]