Singular

system("reference");
ring rng =0,(x),dp;

reference ref1 = rng;
reference ref2 = rng;

// how to check if ref1 and ref2 a tied to same name/object?

> system(ref1, "help");
system(<ref>, ...): extended functionality for reference/shared data <ref>
  system(<ref>, count)         - number of references pointing to <ref>
  system(<ref>, enumerate)     - unique number for identifying <ref>
  system(<ref>, undefined)     - checks whether <ref> had been assigned
  system(<ref>, "help")        - prints this information message
  system(<ref>, "typeof")      - actual type referenced by <ref>
  system(<ref1>, same, <ref2>) - tests for identic reference objects
> system(ref1, "same", ref2);
0
>reference ref3 = ref1;
> system(ref1, "same", ref3);
1

system("reference");
ring rng =0,(x),dp;

reference ref1 = rng;
reference ref2 = rng;
system(ref1,"same",ref2); //0