How to add value labels?

[fkohrt]

I wonder if there's any best practice on how to document the labels of values?

For example, the SPSS dataset demo.sav (can be obtained here) has the following variables:

> dat <- haven::read_spss("demo.sav")
> names(dat)
 [1] "age"      "marital"  "address"  "income"  
 [5] "inccat"   "car"      "carcat"   "ed"      
 [9] "employ"   "retire"   "empcat"   "jobsat"  
[13] "gender"   "reside"   "wireless" "multline"
[17] "voice"    "pager"    "internet" "callid"  
[21] "callwait" "owntv"    "ownvcr"   "owncd"   
[25] "ownpda"   "ownpc"    "ownfax"   "news"    
[29] "response"

Now each of these variables has a label:

> attr(dat$marital, "label")
[1] "Marital status"

Now the marital status is coded with 0 and 1, and the meaning of that is also documented:

> names(attr(dat$marital, "labels"))
[1] "Unmarried" "Married"  

In the documentation of pointblank I've only seen examples of variable labels, but not of value labels. I wonder if there are any existing best practices on how to document these?