[syslinux] Can USBstikA boot USBstkB ?!

[eas lab]

] At this time, Syslinux by itself cannot boot files located on a
] different filesystem volume.

Finally an answer to my simple question - PERHAPS?
What is a "filesystem volume" ?
Why do you change the terminology/definitions of the original question?
Is a "different filesystem volume" on a different <physical device>?

] Using chain.c32, you can load a boot sector (MBR or VBR) located on
] another device.

Thanks for calling it "another device". I can't relocate the Dir with
the files; but IIRC one was *.32. Perhaps it's a 32/64bit problem?

] Since the list of files located in your boot stick did
] not include chain.c32, my assumption (and not only mine, if you
] carefully read some of the prior replies) is that the relevant "old"
] files (e.g. kernel, initrams, etc.) were also located in the same old
] (stolen) boot stick (while your root partition might have been located
] on a different device).

No!! I deliberately avoided confusing you, and only listed sufficient
for you to see:
1. it *IS* about syslinux;
2. the date [syslinux-model];
3. that I had been editing the original cfg-text;

] But, since you have not provided any relevant information (not even the
] content of your old syslinux.cfg nor how exactly you were "editing"
] your boot entries so as to boot some/one OS or another), the above
] paragraphs are only assumptions. In a similar way, prior replies to you
] were also theoretical and very generic.

I had at least 3 sets-of-kernel & initrm on the capable boot-stik,
which I could edit at boot-time to select - as you describe below.
Plus a score of all-but-one commented out line: containing the parameters.

] For example, your old Slackware's kernel (+ initrd files) might had
] been located in the same boot stick, and the boot command _might_ had
] included some indication for the kernel (+ initrd) to find the "root"
] partition (e.g. root=/dev/hdb5 or something else). But, as I tried to
] explain before, this "hdb5" varies depending on the BIOS; in other
] words, it is not always "portable" when changing connections or when
] moving to another PC.

Reading my text: do you think I didn't know that <sdX moves around>;
that's why LABEL/UUID is used.
And why I bypassed that problem, by asking the general/principle question:
 "can *ANY* bootstikA boot a bootstikB".

Your description above approximately describes how I in fact booted
different IDE & SATA from a USBstik, which indicates that your original
statement is false.
There are multiple layers of complexity:
1. can USBstikA boot ANY other device?  Yes: as you partially describe.
2. can USBstikA boot USBstikB? This forum refuse or incapable to answer.
3. can USBstikA boot a USB-adaptor-connected IDE or SATA. Must 1st pass "2"