I’ve got a situation where there are multiple possible tables that a particular rule could be running through. 16.7 in the manual gives these phrases for testing whether or not a particular space in a table is blank:
But what I’m wondering is, is there a way to test whether the “space for it in the table” exists at all? Or to put it another way: Can I test whether a particular column is present in a table? It doesn’t matter whether it’s blank or not, only whether there is a place where an entry could be put.