In the illustrations of the IPA Handbook, this letter may come before a word or syllable to indicate prosodic pitch, and after a word or syllable to indicate lexical tone.
When this letter occurs in ligature with other tone letters, they together indicate the pitch contour of the tone. For example, ˦ means a level mid-high tone, and ˦˥˩ means one that begins mid-high, then goes high and ends low.
Tone letter on Wikipedia.Wikipedia 