Barney,
The beauty of the way it's done in Evernote is, that you define every one of your own triggers. It's not up to the developer per se.

Evernote provides a mechanism to store whatever trigger strings you wish, and matches the string list to everything typed and voila... when the notes finished, so is the classifying.

Evernote allowing you to set strings of whatever sequence of characters you want as a trigger can to some be quite a stumbling block because it makes them have to think about their life fully and categorise everything they do, to arrive at an overall schema with a workable number of such strings. (Coders know this sort of thing and to them this might come somewhat easier because they've had to take apart everything about what it is they're trying to achieve before they can code a part of the whole. Either that or the program is never quite what it was intended to be until the first complete rewrite... aka version 2, is released  :P ).

I've arrived at a limited number of either abbreviations, or the full word if always typed in full, that match the lists I use to maintain the activities in my life and suffix those abbrev's/words with a colon to make them unique. I can read the abbrev or word inplace and it makes good sense. Bit like the creation of the modern teenagers TXT message :P

Example...
21/7/2012. Finished repair on <MyCustomersName> PC. Inv: $47.50 total (Parts $37.50, Travel $10). Used MSI 9550 Vid card, 1 x 2nd hand stick of 512Mb DDR400 to increase to 1Gb. Labour Free: as this ones for a friend.

I can copy the above string into an invoice then leave only the salient details once pasted. There are 2 categories automatically assigned to the note and that is Inv: = Invoices (because thats an activity I will need to do at the end of the day) and Free: = "Who have I done some work for and not charged them". (I do work for friends and some community organisations and don't charge them Labour, just Parts or anything that actually costs me, but I should keep a track of the time that it's taking me so I keep an awareness of free work versus chargeable work).

Evernote still allows a search on any string at any time so I don't have to categorise everything, just the most pertinent points that should have an additional method of grouping.

This way I can still use the word "free" (no colon) anywhere else and it makes sense in the note it's used in but will not be added to the category "Free:".

The 2 points to this are that you can use whatever character you like after the ordinary (English in this case) word, it doesn't have to be the colon and 2nd'ly I'm using the words I'd normally type to make the note anyway but adding a twist that helps uniquely categorise it in the process. I use colon because my hands reach those keys ( SHIFT + : ) naturally with little movement away from their standard resting position at the keyboard.

Yep, yer right.  Establishing that convention (for the developer) might be a bit tricky.  It'd need to be easily typed, and not [often] misinterpreted.  As an example, I use the ` symbol in ShortKeys (a text expander) as a trigger for the abbreviations.  But that character is a part of some languages, so it wouldn't work for everyone.  Language and keyboard constraints make that assigning a trigger symbol a problematic thing.
However, when you have several tags already selected, those tags automagically appear in the tag window for the new note.  Not the best solution, I'll grant, but it tends to work well for my needs.  Thing is, I tend to work within the limitations of the software I'm using - that's why I'll never be a good beta tester  :P - so a lot of potential improvements never occur to me  :( ;) :P.
I'd love to see an app built to your requirements, though ... suspect that would be mucho grande.
Edit for clarification - see strikethrough.

-barney (July 21, 2012, 02:28 AM)

Deciding not to leave any stone unturned, here's links to the sync'ing software mentioned by Barney - for those that may follow in our footsteps :)

Syncless - http://code.google.com/p/big5sync/   (Open Source)
Beyond Sync - http://www.beyondsync.com/      (Payware - $29.95 - 2012/07/19)

<snip> ...  As for replicating across multiple boxes, either Syncless or Beyond Sync (sorry, no links) should resolve that issue - at least it does for me.

-barney (July 16, 2012, 11:24 PM)