Here is an email I received from Bernie Conway(see below). The first idea expressed was discussed by the RRTC and our conclusion was to use the date of the submission of the data.
The 2nd idea expressed is handled in a similar way by us. However, we don't record the number of times a course is adjusted and use a different ID#.
The 2012 IAAF-AIMS Meeting in Kavarna, Bulgaria saw a few changes to the IAAF certification numbering which I have also adopted for Athletics Canada and you may want to consider.
The first is that the year in the certification number is the year that the course was measured. As an example if a course was measured in 2010 but not certified until 2012 the 2010 would be the year showing up in the certification number.
The second change is that if a race undergoes a partial change (large or smaill) and only part of the course is measured, then the new certificate will retain the original certification number but an "a" will appear after the number to indicate a change to the course. For example I measured a 10 km course in 2009 (ON-2009-160-BDC). Last week I measured a new finish from the old 9 km mark, the rest of the course did not change. I sent a new certificate ON-2009-160a-BDC to the Race Director. If another change occurs I can use "b" and then "c" if needed.
These changes enable me to keep tabs on how many years before the course needs to be recertified by an overall ride once the 5 (IAAF) or 10 (Athletics Canada) year limit has been reached. It also allows me to place the new certificate in the same file folder as the original. Finally it allows me a more accurate tally of the number of road races in existance.
It looks like measuring is finished here until Spring. The temperature is in the single digits Celcius during the day and the weather man is indicating rain with the possibility of snow. If you need a measurer for some warm location think of me. Best of health.