42S local label caching

[Dave Britten]

From page 149 of the 42S manual, first paragraph:

"A local label search can consume a significant amount of time, depending on the length of the current program and the distance to the label. To minimize searching time, the calculator remembers the distance from the GTO or XEQ instruction to the specified local label.* This eliminates the searching time for subsequent executions of that same GTO or XEQ instruction."

And the footnote at the bottom of the page:

"*The distance to the label is stored internally as part of the GTO or XEQ instruction. If this distance is greater than 4,096 bytes in either direction (128 for short form lables [sic]; LBL 00 through LBL 14), the calculator cannot store the distance and a search must take place for each execution of the instruction."

How does this work exactly? Is that distance literally stored directly in the GTO or XEQ instruction inside the program? Or is it held elsewhere in memory? How long are these cached branching distances kept? Do they persist between multiple invocations of a program? What about if you XEQ a global label in a different program area? Will local label lookups inside that program be cached if you call that same external program multiple times inside your program?