Question on the History of a Notation

Often when one does field theory, or at least this was my experience, one's first encounter notationally with a field is that they are generically denoted $\displaystyle F$ or $\displaystyle \mathbb{F}$. This of course makes sense for the same reason that **v**ector spaces are generically denoted $\displaystyle V$, **m**odules and **m**onoids $\displaystyle M$, **r**ings $\displaystyle R$, and **g**roups $\displaystyle G$. Moreover, it is common (in accordance with sets) that these structures should have a capitalized letter. That said, it seems to be a universal notation among more advanced field theory books (especially those dealing in algebraic number theory) to denote fields by $\displaystyle k$--not **f** and not capitalized. Is there any particular reason for this? Is it possible that it is for the same reason that $\displaystyle \mathbb{Z}$ is the integer (zhalen)?