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Category codeDescription Standard LATEX/TEX
0 Escape character—tells TEX to start looking for a command\
1 Start a group{
2 End a group}
3 Math shift—switch in/out of math mode$
4 Alignment tab&
5 End of lineASCII code 13 (\r)
6 Macro parameter#
7 Superscript—for typesetting math: $y=x^2$ \(y=x^2\)ˆ
8 Subscript—for typesetting math: $y=x_2$ \(y=x_2\)_
9 Ignored characterASCII 0 <null>
10 Spacer ASCII codes 32 (space) and 9 (tab character)
11 Letter A...Z, a...z, (and thousands of Unicode characters)
12 Other 0...9 plus ,.;?" and many others
13 Active characterSpecial category code for creating single-character macros such as ˜
14 Comment character—ignore everything that follows until the end of the line%
15 Invalid character, not allowed to appear in the .tex input fileASCII code 127 (DEL)

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