How to correctly specify an array of elements in a GET parameter?

Question

Computer networks

I have seen three possible cases of an array declaration:

1. ?param=[1,2,3] problem: what about strings?
   
2. ?param[]=1¶m[]=2¶m[]=3 cumbersome
   
3. ?param=1¶m=2¶m=3 it is not clear that the parameter is an array
   

Is there some standard how an array should be specified?

Answer 1

I specify ?param=[1,2,3] or ?filter=price[777,3127];manufacturer[16].
And then I break implode(). Or you can write a function.