This response from the library messages shows at some weird times.
If you type “put me”, you get “I didn’t understand that number.”
There’s no reference to library message 29 in the standard rules, so I don’t know how to check what things cause it.
“Didn’t understand that number” is one of the parser errors.
Apparently the game thinks there should be a number at a certain point in that command—as in e.g. ERIS, PUT FIVE APPLES ON THE TABLE—; but it can’t find one, so it protests.
To find out exactly which word offends the parser, try typing the debug command TRACE, before entering the offensive command. That will print run-time information about what the parser is doing.
Simply TRACE will do here; but to look deeper into the workings of the parser you can use TRACE 4, TRACE 5 or TRACE 6–or, for a shallower look, TRACE 1 or TRACE 2 (TRACE is the same as TRACE 3).
TRACE OFF will, well, switch the trace function off.
Not in 6G60 on Windows. I get “I didn’t understand that sentence.” Most likely you’re either using an extension that handles numbers, or your own code does so.
And thanks for mentioning trace. I love seeing the actual I6 grammar lines. Makes me feel all nostalgic – plus, it’s useful.
–JA
Good show. I’ve recalled the command for some time, but forgot its actual name. Is the Trace command documented anywhere?
It’s discussed briefly in the DM4, the official manual for Inform 6.
I honestly can’t recall where I heard of it (though it can’t be very long ago).
The only written documentation I can find right now is in the Inform Designer’s Manual (Inform 6 that is – downloadable from the old Inform 6 website). It’s in §7.5 (p. 100) of that document (though I think the trace levels 0–5 mentioned there corresponds to levels 1–6 in Inform 7).
Thanks for the trace info, Felix.
Jim, you’re right. I went immediately to a likely suspect, ‘Numbered Disambiguation Choices’ by Aaron Reed, and turning it off made ‘put me’ give ‘I didn’t understand that sentence.’
I’ve been wondering about this error message myself. Not sure whether numbered disambiguation is worth having these extra errors…
–Zack
The handy-dandy Programmer’s Manual, perhaps? 
Doubtless!
I wrote Aaron about the bug and he promptly responded with a bugfix. I expect you’ll see version 4 of the extension made public soon.
TRACE! I knew there was a command like that, but I couldn’t find it in the documentation or the index (must have missed it when I was searching the Actions index for testing commands).
I think the Actions Index needs a Testing Commands section, and testing actions should be documented there. I’m out of votes on Uservoice - does anyone want to suggest it?