Re: PCB version control

On 3/24/2025 3:48 PM, Don Y wrote:

On 3/24/2025 3:01 PM, Joe Gwinn wrote:

I’m with you—it’s good for stuff to be human-manageable.

>
Below some size, this can be done.

 For most non-trivial businesses, that size is quickly exceeded.

And, when a new packaging (or fabrication) technology comes
along, you'll be ready to REVISE your numbering scheme to
accommodate *that*!

Will you ever know if a particular identifier maps to a *real*
device?  I.e., are there HOLES in your numbering system??

The more you encode in a part number, the more brittle your
numbering scheme becomes.  And, the more reliant you become on
fallible, REPLACEABLE human beings.

 From _Engineering Documentation Control Handbook_:
    "The most critical of these issues is that, over time, the significant
     numbering systems tend to break down.  As time passes, variations arise
     which were not foreseen. One digit was set aside where two are now needed.
     Significant numbers thus tend to lose their significance. They no longer
     do the classification coding function intended by their inventors."
 From _Engineering Documentation Control Practices and Procedures_:
    "Typically, companies run out of numbers in certain categories of a
     significant number. Also, a non-significant part number is more
     cost-effective to use than a significant part number."
 From _Bills of Materials: Structured for Excellence_:
    "The solution is to use shorter non-significant part numbers. We have
    found that part numbers of 5 or 6 digits are the most effective."
 From _Manufacturing Data Structures_:
    "Another important point about item numbers is that they should be as
    short as possible. Part numbers are keyed, copied and used as verbal
    identifiers. The shorter the numbers, the more accurate people can be.
    Obviously, the greater the number of digits in a part number, the greater
    chance of error. We also recommend that only numeric digits be used."
 From _CMII for Business Process Infrastructure_:
   "Identification numbers are preferably short, not long. The characters
   that make up the number are preferably numeric, not alpha. Any symbols
   to be used with the numeric characters are preferably limited to dashes."
How much "significance" can you embed in an identifier when the TOTAL length
of the identifier should be "SHORT" numerics?
When I first started off in business, I opted for 8 digit identifiers
(because DOS filenames of 8 characters were readily supported and because
NUMBERS are easier to track than arbitrary character sequences).
I figured 6 digits was too few; 8 was likely too many (but not prohibitively
costly to support with the technology available at the time -- Paradox,
dBase, etc.)  And, variable identifier lengths means you never really
know if you have a valid identifier unless "something" can check it for you.
(Are resistors xxxx-yyy?  Or, xxxx-yy-z?  Or...)
I've since scaled this back to 7 digits plus a check digit (the issuing
authority ensures the correct check digit is created for any 7 digit
"serial").  The check digit helps catch the case of numbers that may
have been transcribed (handwritten!) poorly.
In hindsight, I should have started with 1000000 instead of 0000000 as,
too often, I have to convince some piece of software NOT to drop leading
zeroes in those identifiers!  :<
In a hardware-oriented business, it's hard to actually *use* that
many identifiers; how many DIFFERENT screws do you use?  If you opt
to use *one* clutch head screw in a design, do you have to set aside
a whole block of numbers to SIGNIFICANTLY encode head size, thread
pitch and length?  What about when someone opts to use a Pozidriv
fastener?  (all those silly numbers -- and numbering SCHEMES -- created
for parts that you will likely never use!)
OTOH, if your "products" are primarily "paper", you can use hundreds of
identifiers in short order; any object that needs to have its presence
in an assembly identified and its configuration changes preserved.
E.g., I use numeric file names for each module, specification, datasheet,
etc.  I create symlinks (or hardlinks, as appropriate) to give them
"familiar names" (like stdio.h).  But, these identifiers don't *formally*
exist.  (WHICH "stdio.h" are you talking about?)
If your company ad product line dies with you (many do), then you can do
whatever you want (Ikea gives "names" to products).  But, if you want
your designs to persist after you've left the business (or, if you
have to deal with certification authorities or investors who want
to purchase your business for more than "value of inventory on hand"),
then you want systems in place that don't rely on silly quirks
put in place historically.