In subsection "7.1.6 Recoding string/numeric variables" (book, third edition) on page 139 there is the following sentence in the text:
"If in one data set observations for the Republic of Korea are referred to as “Korea, Rep.” and in another they are labeled “South Korea”, R will not know to merge them."
The last part of the sentence is probably missing the word "how" --> "[...], R will not know how to merge them."
In subsection "7.1.6 Recoding string/numeric variables" (book, third edition) on page 139 there is the following sentence in the text:
"If in one data set observations for the Republic of Korea are referred to as “Korea, Rep.” and in another they are labeled “South Korea”, R will not know to merge them."
The last part of the sentence is probably missing the word "how" --> "[...], R will not know how to merge them."