There are some sans-serif fonts where serifs are used sporadically:
My questions are:
Are these considered real serifs, i.e. will typeface designers call them serifs or are there other names?
Is there a name for the phenomenon, meaning using "serifs" in sans-serif" fonts? Can I filter to find these "mix" fonts by using some keyword?
I found the letters I, T, S, Y, and C using such "serifs". Are there other common "serifs-in-sans" letters?