What do following snippets of code do in Math ML files? I removed those lines and it still worked fine for me.
<mo>⁡</mo>
<mo>⁢</mo>
<mo></mo>
Answering to any of them or just letting me know what they are would be very much appreciated.
The first two are ⁡ function application and ⁢ invisible times. They help indicate semantic information, see this Wikipedia entry
The last one, , could be anything since it lies in the Unicode Private Use Area which is provided so that font developers can store glyphs that do not correspond to regular Unicode positions. (Unless it's a typo and really 6349 in which case it's a a Han character.)