weired dash in references

[janscience]

In the abstract body text (jason file) I got "... clock$^3$$^−$$^5$". This persists after running gca-tex on it. pdflatex then breaks:

! Missing { inserted.
<to be read again> 
                   \begingroup 
l.105 ... They exhibit a circatidal clock$^3$$^−
                                                  $$^5$ plays a role in thei...

If I replace the dash (which is not a normal dash) by a normal dash or by {--} it works.

[janscience]

I have fixed it by adding a \newunicodechar to the tex file (in my pullrequest #11).

However, I wonder where this comes from. Since I have not uploaded an abstract myself, I do not know how references are entered. Is the unicode dash something the user typed in (then my solution is the right one), or is it something that is automatically generated by the web interface or somewhere along the toolchain - then somebody should fix it.