What does "effective enumeration" in Turing machines mean? what is meant by EFFECTIVE ENUMERATION i have comes across this word when I was reading about enumerators for Turing machines is it same as LEXICOGRAPHIC ORDER? 
so effective enumeration is possible for recursive sets but no recursively enumerable sets?
i came across this in this question of a competitive exam 

L1 is a recursively enumerable language over Σ. An algorithm A effectively enumerates its words as ω1,ω2,ω3,….
 Define another language L2 over Σ∪{#} 

{wi#wj ∣ wi,wj∈L1, i &lt; j}.

Here # is a new symbol. 

Consider the following assertions.

S1:L1 is recursive implies L2 is recursive

S2:L2 is recursive implies L1 is recursive

which of the following is true ?
One way to approach EFFECTIVE ENUMERATION is as following. Let $L=\{a_1, a_2, \dots\}$ be a set/language. Then we (effectively) enumerate $A$ if we can construct a TM $M$ which prints out (enumerates) all elements of $L$ on the tape, say in the following way: $a_1$#$a_2$#$a_3$#$\dots$. The order of the elements is not important. What is important is that any element of $L$ will eventually be printed on the tape, meaning it must not be a  LEXICOGRAPHIC order.