Is this case considered an ambiguity or not?

Question

From the answer to my question How are PGN ambiguities handled?:

In the case of ambiguities (multiple pieces of the same type moving to the same square), the first appropriate disambiguating step of the three following steps is taken: ...

After reading that, a new ambiguity surged from that disambiguation, it is not clear what would happen if the pieces that look like they can move to a same square are all pinned except one piece, is then a need to disambiguate even if only one of those pieces can legally move in there?

Here is an illustrated example:

[FEN "4k3/8/8/8/8/8/8/q2NKN2 w - - 0 1"]

Should I use Ne3 or Nfe3?

Answer 1

Ne3 is perfectly fine, every normal pgn viewer knows legal moves and will perform it correctly.

Answer 2

While it's not ambiguous (only Nfe3 is legal), it is better to be specific with Nfe3. Successful software can deal with both Ne3 and Nfe3, but not every pgn parser is perfect, and some beginners will appreciate the additional guidance.

Answer 3

just found this:

8.2.3.4: Disambiguation

Note that the above disambiguation is needed only to distinguish among moves of the same piece type to the same square; it is not used to distinguish among attacks of the same piece type to the same square. An example of this would be a position with two white knights, one on square c3 and one on square g1 and a vacant square e2 with White to move. Both knights attack square e2, and if both could legally move there, then a file disambiguation is needed; the (nonchecking) knight moves would be "Nce2" and "Nge2". However, if the white king were at square e1 and a black bishop were at square b4 with a vacant square d2 (thus an absolute pin of the white knight at square c3), then only one white knight (the one at square g1) could move to square e2: "Ne2".

http://www6.chessclub.com/help/PGN-spec

Answer 4

It is not ambiguous for only one Ne3 is legal.

Answer 5

Formally, both Nfe3 and Ne3 are valid notations in this situation. As far as I know, the convention is to write Ne3, because the Nd1 cannot move due to the pin Qa1-e1. But it is not impossible that someone would still scribble down Nfe3 in the score sheet and that is what you would find in your PGN file. Chess software would write Ne3 if you would present them with this position. If I would have this position, I would write Ne3 in my score sheet, because this follows the notation convention.