The dxf documentation can be very confusing at times and very often it lacks a lot of info. It seems that the block you are talking about, the one that makes the actual drawing of the dimension, in R12 dxf version the text that holds the measurements (or
optionally any other text the user might have written) is saved as a TEXT entity while in version 2000 and newer is saved as an MTEXT entity.
Looking at the file generated for a linear dimension (different dimension types will vary):
- in R12 file the block (*D2 in my sample) is made of 4 lines (reference lines), 2 solids (the arrows), 3 points (dimension reference points) and an insert which block (*U3) holds the text. It might be this way (this is just a guess) so the dimension can
have multiple text lines split in several TEXT entities.
- in R2000 and newer the block has the same number of entities but instead of using an insert that holds the dimension text, it uses directly an MTEXT entity.
I don't know what might happen if you use a R12 rules in a dimension saved as a dxf 2000 version. The use of MTEXT is an upgrade while TEXT entities only hold a single line, MTEXT entities can hold many. Since I have dropped support for R12 files I would
follow the 2000 route, but the MTEXT entity is not implemented (we can work on it).
There are no stupid questions only stupid answers.