What does abbreviation $ecnd$ represent in the book "Real variable and Integration" of the author $ John \ Benedetto$?

Question

In John Benedetto's text: "Real variable and Integration", he refers to a property of functions which he calls "ecnd". This doesn't seem to be a universal definition, probably his own. It occurs early in the text but I cannot find a definition. Can someone clarify what this may mean?

Note:

Here $\text{ecnd}$ means everywhere continuous nowhere differentiable functions. One such example is $f(x)=\sum \frac{1}{k^2} \sin (k^2 \pi x)$.

See section $1.3.2$, $ \ Sets \ \ of \ \ differentiability \ $ of the above book. (pages from $25-27$)

Answer 1

According to the index of notations, it is defined in Section 1.3.2 of the said book: