At NBS recently, we've been doing 
quite a few webinars. One of the most frequently asked questions has been about how practices are using codes to group similar types of systems together.
For example, if your project has 5 of 6 different 
floor covering systems, then giving each of these a code such as FCS001, FCS002, FCS003 etc... so these codes can be used in planning sheets, annotations, schedules etc...
Examples of this are shown below...
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| Planning the specification and drawings | 
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| Annotating drawings from a linked model and specification | 
So to get further feedback, I posted a request within our NBS Chorus ideas forum.
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https://support.thenbs.com/support/discussions/topics/7000040360
(to follow link you need NBS ID linked to Chorus subscription)
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| Chorus ideas forum | 
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| Request for contributions | 
It was great to then see some of our subscribers passing their codes to us to create a 'crowd sourced' Google Sheet. Thanks to Patrick C from AHMM for the list below...
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| Architectural codes | 
Lewis from Hydrock then pointed me in the direction of Carl from CIBSE who provided more...
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| Building services codes | 
It's an interesting subject. I personally really like the balance between Uniclass 2015 for the in-depth classification, but then an accompanying short code (a bit like a car registration plate) for packaging items and quickly verbally referring to a specific type.
Please keep the feedback coming in. 
Message me on Twitter or drop me an email into NBS.