Understanding Society User Support

Hi,

I’ve got a quick query regarding a missing variable in a USoc libname in SAS:

When using the most up to date libname for USoc /surveydata/ukda/us/Waves_1_10_2009_2019; the variable birthy is present, e.g. in b_indall b_birthy is produced in output data, but when using the libname /surveydata/ukda/us/Waves_1_4_2009_2013; birthy is not present. I know that the most recent libname should always be used but would you happen to know why this is the case or if this shouldn’t be happening? Would it be that the variable name has been changed since the older libname was released? And can USoc variables change names since the start of the survey in 2009 and thus between libname update too?

Thanks for your help.