See (p1,realdom) for information about the use of this key. All calls to the DOMAIN_TOOL are prompt. See (p1,synergism) about why domain tools are non fundamental {not needed in theory}.

DOMAIN_TOOL(0;NK==>c;DK) produces a domain key that designates the node designated by the node key NK. c is zero if NK is a node key and −1 otherwise. The databyte of DK is 0.

{Rights Amplification}If (E is a start key and n is 1, or E is a return or fault key and n is 2, or E is a domain key and n is 3) and E's brand {C0 of E's domain} is B then DOMAIN_TOOL(n;E,B ==> b;N) returns the databyte of E in b and returns a node key {with 0 databyte} to E's domain root. Otherwise the call returns −1 in b and DK(0) in N.

- See (p3,res-ex) about why restart keys are excluded.

- Fine print: If the segment or meter node is one of the nodes of the jumper's domain, c=−1 and s=0.

See (scne) concerning exclusion of restart keys.

{ni}I propose that if S is a segment key with the no-call bit on then a sense key to the node be returned.

See (p1,realdom) for reasons for restricting this entry. See also (p2,dc) and ((p1,worsejump) SC = 51).