Very obscure indeed. If you see his paper in English (published in 1959), you can see the following (page 43):
By checking other variables, you can confirm that the variable letters are equivalent in this and your reference. Then, $E$ stands for "all non-wage income, taken at the moment received, instead of take when earned".
This is a standard differentiation between the time an income has been accrued ($Z$) and when it has actually been received ($E$).
You can see more about these definitions later on in the document. In page 49, you find an explanation on how these are calculated (19 is $Z$, 20 is $E$; see table in page 47-48):
It seems the author is assuming that income is received one further year after is is accrued. However, the text seem to me rather obscure. He mentions a "pamphlet regarding this working method which will be published later." (p.42). You might want to trace that one down.