There are a lot of similarities between Z540.3 and ANS/ISO/IEC 17025:2005.....however, they are not quite the same.....some requirements in 17025 are more detailed than in Z540.3.....Z540.3 also has most of the requirements of MIL-STD-45662A, where 17025 does not.....17025 does include the QMS requirements of G25 with additional detail and a couple of extra requirements.....PLUS it adds the technical evaluation side that G25 did NOT have.....
Z540-1 is a combination of ISO Guide 25 and MIL-STD-45662A, both nearly word for word.....and both MIL-STD-45662A and ISO Guide 25 are long since retired and put out to pasture.....even though they still show up in legacy contracts.....
Also, 17025 covers test labs also.....Z540 is calibration also.....a fair part of the reason for including some requirements and not others, with respect to commonality.....
I don't have a definitive date for the retirement of Z540-1 yet, I will get that at NCSLI and pass it along.....
Hope this helps.
Hershal