Making a chart of GSB/XEQ/GTO/LBL/RTN functionality and quirks

[Dave Britten]

I'm working on an Excel table that compares the behavior, functionality, and quirks of GSB/XEQ, GTO, LBL, and RTN across all the programmable models. This is the checklist I've got so far:

GSB/XEQ
Max depth (including user-invoked routine)
Call stack overflow is error (Do any models throw an error, or do they all silently discard the oldest call?)
SST executes entire subroutine call
Labels
Line numbers
GSB/XEQ indirect to label
GSB/XEQ indirect backward steps
GSB/XEQ indirect forward steps

GTO
Labels
Line numbers
GTO indirect to label
GTO indirect backward steps
GTO indirect forward steps
RTN with empty call stack
Stop in place
Stop at top of program

LBL
Duplicate labels allowed
Label search starts from program pointer
Label search starts from top of program
Label searches cached

Special Notes
GTO nonexistent label jumps to top of program
A-E key to nonexistent label starts at top of program
Programmed A-E to nonexistent label jumps to top of program, next RTN stops program
R/S without A-E skips first RTN
Tests skip two steps if false
3rd subroutine call returns to 1st routine
GTO 00 stops program
SST of GSB allows only one RTN
GTO 00 acts like RTN
GTO and XEQ require a label and line number

Are there any other features or peculiarities I should list? I know some older models don't terminate an x-register entry on R/S (e.g. the 25), but I'm not sure if any keep a pending entry open on GTO/GSB, so I don't know where best to categorize that yet.