·
The dot that floats mid-line — Catalan can't live without it.
The middle dot separates without sinking: in Catalan it is a working letter — col·legi, paral·lel — marking that the two els do not form the digraph. Elsewhere it is the discreet separator of horizontal lists and footers — including this site's.
The mistake it corrects is the full stop promoted to separator: col.legi trades orthography for punctuation. The entity is ·.
Wrong: col.legi · para.lela (a low dot faking the median)
Right: col·legi · paral·lela (the dot floats between the els)