The diagonal slash "/" used as the bar between numerator and denominator of an in-line fraction (Bringhurst 1997, p. 284). The solidus is also called a diagonal.
Special care is needed when interpreting the meaning of a solidus in in-line math because of the notational ambiguity in expressions such as 
." is intended to denote 
,
.
Common examples of failure to parenthesize include 
(where E is energy, k is Boltzmann's constant, and T is temperature; Arfken 1985, p. 950), its variant 
(where c is a constant and 
is wavelength; Weast 1981, pp. F-109 and F-111), the exponent 
in the normal distribution (where 
is the standard deviation; Hastings 2000, p. 217). Other miscellaneous examples occur even in the standard references for computer math systems (e.g., Wolfram 2003, pp. 776, 779, and 787).
Division, Fraction, Long Division Symbol, Obelus, Slash, Vinculum, Virgule
Arfken, G. Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, 1985.
Bringhurst, R. The Elements of Typographic Style, 2nd ed. Point Roberts, WA: Hartley and Marks, p. 284, 1997.
Grossman, J. (Managing Ed.). "Solidus." §5.122 in The Chicago Manual of Style, 14th ed. Chicago, IL: University of Chicago Press, p. 189, 1993.
Hastings, K. Introduction to Probability with Mathematica. Boca Raton: Chapman & Hall/CRC, 2000.
Weast, R. C. (Ed.). Handbook of Chemistry and Physics, 61st ed. Boca Raton, FL: CRC Press, 1981.
Wolfram, S. The Mathematica Book, 5th ed. Champaign, IL: Wolfram Media, 2003.