# How to use italic correction for slanted letters (\textsl)?

Is there italic correction specific to slanted letters (\textsl)? I always use \textsl for slanted letters (not \slshape), so would redefining \slshape to add an \/ at the end be the easiest way of adding italic correction to slanted letters in my documents?

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i believe that any font that has a slant defined in a tfm file will handle an italic correction automatically if accessed in pdf(la)tex or the original tex implementation. things may be different with xetex or luatex. –  barbara beeton Jan 15 '13 at 19:45
@barbarabeeton as far as I know, xetex does not (when using OpenType fonts) create fake italic corrections from the font data; whereas LuaTeX does, but only for the Italic features. As a result $\mathrm{f_i^i}\mathit{f_i^i}$ with Latin Modern fonts give different results in the three engines, XeTeX, LuaTeX, and PDFLaTeX (italic corrections are important in math mode). –  jfbu Jan 15 '13 at 21:27

Every letter has an associated italic correction, It is usually non zero for slanted letters. LaTeX automatically inserts \/ at the start or end of \textsl (and all similar commands such as \textrm) if the font slope changes from upright to slanted or vice versa.
I sometimes need to add a small \hspace{0.5pt} or \hspace{1pt} after \textsl when it occurs in section titles. I have a feeling that its appearance in boldface and upright styles is slightly different (when I look in the TOC and in the actual heading, the correction/adjustment seems subtly different), but I cannot prove it. –  Lover of Structure Jan 17 '13 at 11:12
The display tittle will use a different font so the italic correction will be different (not necessarily scaled linearly with the font size) You can use \showoutput and get a readable representation of the output and see any kerns applied. Sometimes in titles you do need fine tune the spacing for the best effect. –  David Carlisle Jan 17 '13 at 11:23