You can use format codes available in AutoCAD in order to define a user description. To apply the formatting, use paragraph format codes:
Format code Purpose
\0...\o Turns overline on and off
\L...\l Turns underline on and off
\~ Inserts a nonbreaking space
\\ Inserts a backslash
\{...\} Inserts an opening and closing brace
\Cvalue; Changes to the specified color
\File name; Changes to the specified font file
\Hvalue; Changes to the text height specified in drawing units
\Hvaluex; Changes the text height to a multiple of the current text height
\S...^...; Stacks the subsequent text at the \, # or ^ symbol
\Tvalue; Adjusts the space between characters, from .75 to 4 times
\Qangle; Changes obliquing angle
\Wvalue; Changes width factor to produce wide text
\A Sets a valid alignment value: 0, 1, 2 (bottom, center, top)
\P Ends paragraph.
Multi-line text objects use word wrap to break long lines into paragraphs. For AutoCAD to break lines automatically and not create a new paragraph, the line should end with either a backslash (\) or a space character.