packageVersion("yspec")[1] '0.5.3.9000'date()[1] "Wed Jun 8 08:29:19 2022"
yspec is an R package to help you manage and utilize documentation for analysis data sets of the kind that are frequently used in pharmacometrics. The y in yspec stands for yaml: data set definitions are written in a standard format using yaml language.
You can find documentation for yspec here.
Source
The yspec package is maintained here. The code for this book is maintained here.