Caret

[…] the more conventional semivocalic j and the caret (ˇ) respectively.

The caret (ˇ), háček, is used over the following consonants: c, d, n, t, r, s, and z to indicate the soft sound. The caret (ˇ) is also used over the vowel e (See Pronunciation II, b, p, v).

In contemporary Czech, the “hook” or caret is no longer in use for lower-case t and d when the latter are palatal; instead, an apostrophe is used (t’, d’) This development is clearly connected with the practical difficulty encountered in printing a caret over letter stems that are too thin.