[Borek]

have you heard such a term? That's direct translation form Polish and I am not sure if it is used in English. The idea is that in the lab practice you often use one single volume pipette with one volumetric flask. To get high accuracy of the work you should use calibrated glass. Once you know exact volume of the pipette and flask, instead of using volumes you just calculate the fraction pipette volume/flask volume once and you use this number in calculations whenever needed. In Polish this fraction is called commensurability - is it called this way in English? Google says "no".

Is the idea still used in analytical labs?

[JGK]

I would suggest it dates from an era when volumetric glassware was in its infancy. Possibly, when a local glass-blower may have been employed to make laboratory glassware (rather than large manufacturers used these days). this glassware would have to be calibrated before use.

These days, highly accurate pre-calibrated volumetric glass flasks and pipettes can be purchased at a reasonable cost compared to previous eras. Indeed, the father  one of my childhood friends was a glassblower and was subcontracted by Pyrex (Corning) to hand make volumetric flasks which were shipped back to Pyrex to be calibrated.

[Borek]

I think that's not that easy. Class A glassware have a tolerance in the ±0.2% range (10 mL pipette), that means individual pipettes can legally differ by 0.4%. Compare ASTM E287-02 standard specification.

[Train]

I haven't heard the term commensurability, but I vaguely recall reading something about calibrating volumetric glassware by weight.  I've never had to do it, though. 

According to a book I'm reading (Statistics and Chemometrics for Analytical Chemists), instrumental sources of error tend to overwhelm glassware error so that error from glassware becomes negligable.  However, I'm generally disappointed if the RSD of my HPLC run is more than 0.2%, so I'm not sure about that.  In my lab, the use of 1 mL volumetric pipets is discouraged.

The book does say that "with all precautions taken" you can get RSD's a low as 0.01% from wet chemistry, which is pretty impressive but probably overkill for most applications.

[Borek]

I haven't heard the term commensurability, but I vaguely recall reading something about calibrating volumetric glassware by weight.  I've never had to do it, though.

Very general outline:

http://www.titrations.info/volumetric-glass-calibration

In my lab, the use of 1 mL volumetric pipets is discouraged.

And what pipettes are encouraged?

The book does say that "with all precautions taken" you can get RSD's a low as 0.01% from wet chemistry, which is pretty impressive but probably overkill for most applications.

AFAIK not for volumetric methods. More like gravimetric.

[Train]

In my lab, the use of 1 mL volumetric pipets is discouraged.

And what pipettes are encouraged?

Whatever the method says as long as it's >1 mL.  The idea I guess is that the relative error is too large for 1 mL (and 0.5 mL) pipets.