user-1: I just thought about something where two knight can go to the same square. Let say if a white knight is at c3 and a black knight is at b2. They both can go to a4 square. My question is that if I am play in the blind mode and typed
na4

and press enter, how does the chess engine know which knight I moved? Is it matter at all for chess engine to know this?
Note I am playing chess at lichess.

user26806: In algebraic notation, you must specify either the file or rank of the specific piece you'd like to move if an identical piece can also move there.
in the following image, there's a knight on c6 and another knight on e2. There's an arrow going from the f2 knight pointing to the d4 square.

if you'd like to specify this move, then you'd write

N2d4 or
Ned4

In some rare cases you must name both file AND rank. This usually happens when there are 3 of the same pieces on the board, in most cases; 3 queens.
In the following image there are 3 queens, one on d3, another on d7, and another on f7. There's an arrow going from the d7 queen pointing to the f5 square.

this move would be:

(Q)d7f5

The "Q" before "d7f5" is redundant because only a single piece can possibly be on the d7 square so you can just leave it out.

-1: <p>I just thought about something where two knight can go to the same square. Let say if a white knight is at c3 and a black knight is at b2. They both can go to a4 square. My question is that if I am play in the blind mode and typed</p>
<pre><code>na4
</code></pre>
<p>and press enter, how does the chess engine know which knight I moved? Is it matter at all for chess engine to know this?
Note I am playing chess at lichess.</p>
 26806: <p>In algebraic notation, you must specify either the file or rank of the specific piece you'd like to move if an identical piece can also move there.
in the following image, there's a knight on c6 and another knight on e2. There's an arrow going from the f2 knight pointing to the d4 square.
<a href="https://i.stack.imgur.com/frLV7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/frLV7.jpg" alt="enter image description here" /></a></p>
<p>if you'd like to specify this move, then you'd write</p>
<ol>
<li>N2d4 or</li>
<li>Ned4</li>
</ol>
<p>In some rare cases you must name both file AND rank. This usually happens when there are 3 of the same pieces on the board, in most cases; 3 queens.</p>
<p>In the following image there are 3 queens, one on d3, another on d7, and another on f7. There's an arrow going from the d7 queen pointing to the f5 square.
<a href="https://i.stack.imgur.com/UF1fp.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UF1fp.jpg" alt="enter image description here" /></a>
this move would be:</p>
<ol>
<li>(Q)d7f5</li>
</ol>
<p>The &quot;Q&quot; before &quot;d7f5&quot; is redundant because only a single piece can possibly be on the d7 square so you can just leave it out.</p>
