Calibration labels are 1950s military type process thinking.   I have observed those who simply place stickers on all assumed equipment just prior to an audit, with auditors assuming everything is calibrated.   its nonsense.    Calibration stickers are messy, sticky goo on ones most expensive insturmentation.   Further they usually will not survive continual shop floor use and handling, becoming illdgable or falling off all together. 

Looking at the current ISO MSS there are two requirements in clause 7.1.5 

1- General clause - Determine and provide resources to ensure valid and reliable results when M&M is used to verify conformity to requirements .... This is not a requirement for traceable calibration, this requirement is explained in (a) and (b),  the requirement (a) being suitable (the correct discrmination) and (b) maintained to ensure fitness for purpose (legal wrangling for tool maintenance)  Finally maintaining documented information as to fitness for purpose.   This does not mean a calibration sticker. it simply means proving documented evidence of continued fitness for purpose. aka did someone at some point (a point which the organization decides) check the gage to assure its still functioning or capable of functioning?   That its in plain english terms the M&M instrument is not beatup or bunged up to the point its no longer functional (aka ensure fitness for purpose), and was that check documented?   

This requirement would apply to all M&M gages which verify the product meets requirements (aka the gage is relied upon to relase product to the customer).  The determination how and when to check an instument for its "continued fitness for use" is left to the organization.   That decision is based upon reasonable expectations of damage which might occur based upon the environment the gage is sublect to.   One extreme would be an envrionment where the gage is banged about on an assembly line, as it swings from an air line being banged about on items in close proximity (tables, feed rollers etc) and the opposite being an instrument which is fixed (stationary) which is not in an environment where it might become damaged (ie a pressure gage attached to a pipe that is not subject to impact or other damage),  The first gage would require a check far more frequent than the latter.   One might be a weekly check and the ogher an annual or by annual check.   Remember if the gage is used to record the result of inspection, then be smart enought to include with that inspection at some interval, a record to gage was checked.    No stickers required ....

2- starts out with the term When traceablility is a requirement.  or determined to be essential, this is the requirement for calibration of an M&M instrument and it has two initial tests (its either required or determed by the organization to be essential)  Requirements come from customers or legal entiies and determined to be essential is related to the risk of neglegence (aka  the organizations duty of care). 7.1.5.2 (b) only states "Identified in order to determine their status"  It does not state by whom or how.   Therefore calibraion stickers are not a requirement.   The gage simply needs to be identified so its status of calibration can be determined.   The standard further does not indicate that an operator be the one to determine the status of calibration, that decision is left up to the organization, who determines calibration status. 

Since all M&M tools are required to be checked #1 at come point in time and since some M&M tools are required or determined necessary to be calibrated at some point in time, then what is the harm for incorporating these two events together?    If the M&M gage is identified and it can be determined that it was checked and calibrated? are stickers really necessary?    The reasonable answer to that question is of course not