Multiple variable assignment in q

Question

This code looks like multiple variable assignment:

d:`a`b`c!1 2 3
d[`a`b]:10 20

Why is it working this way? And why it is not the same as (a;b):10 20 (which doesn't work)?

I suppose the 2nd line will make only temporary assignment - do not actually replace values. But it will.

Answer 1

It's indexing at top level and assigning new values so it would be the same as:

q)@[`d;`a`b;:;10 20]
`d

which also works for global variables in the root context

q)@[`.;`a`b;:;100 200]
`.
q)a
100
q)b
200