Note: When a variable name is given for time 1 and a
"+" for time 3, the variable was also present at time 3, and the new
variable name can be composed by simply replacing the prefix "*1" by
"*3". Whenever a "-" is found in the tables, the variable was not
present at the time in question. In cases where the variable name was
changed at time 3, each of the names is listed in the appropriate
column.