Just wanted to add that you should never assign any meaning to a number. Every collection out there has items that were numbered out of sequence. It’s impossible for all numbers to be correct. You can’t rely on accession number for anything but to help you find the information about an object. Then you can go to the file and find the year something was donated, how many items were donated, etc. So, in the end it really doesn’t matter what number you give an object. It’s just a number. (I know a lot of people disagree with me on this but that’s the conclusion I’ve come to.)
That said,PastPerfect makes it really easy to deal with this with it’s “old number” and “other number” field. That way you could give an object a completely random number and still be able to find it if you have the old number. The most important thing is that you make the new numbers simple (forget about adding letters, numbers, etc. to the end of the number, besides again you’d be adding meaning to the number) and as it’s already been pointed out, document your reasoning.
Here’s what I would do. If the “71” means 1971 and you are sure of it, I would do my best to keep the objects in order but start with 1971.001.001 and continue from there. If you know the donor, I’d make a separate accession for each set of objects that came from that particular donor. (It was unclear in your original message if they were grouped together by type of item or by donation.) Similar to this:
1971.001.001 to 1971.001.006 = coin purses (or if each coin purse came from a different donor, I’d use this number for everything from one donor, regardless of the item’s old number)
1971.002.001 to 1971.002.002 = plates
I do this a lot if I have items that I know came in a certain year but have no idea the sequence and just make a note of that in the file. If I don’t know the date at all, I just pick a year when I have definite proof that it was here and go with that. For example, I use 1999 for ALL items that I’m positive were here before 1999 but that I have no record of the exact year. 1999 was pretty much the year when things started being recorded better so nearly everything I have that doesn’t have a date received can be given a 1999 accession number.
I make sure there’s a note similar to this one with each 1999 accession record in PastPerfect: “The correct year of donation is not known. 1999 was chosen as the accession year because the items were definetly donated to the repository by this time.”
Here’s another example of one of my notes: “The date of acquisition for this item is unknown. However, it is known that it was in the collection prior to 12 Sept 1993.” (I ended up giving this item a 1993 number even though 1993 may not be the actual year it was donated, but when you don’t assign meaning to the accession number it really doesn’t matter.)
Does this make sense?