The siunitx package has already been extremely helpful to me for formatting tables containing numbers and I now use the S-column in nearly every table of my thesis.
However there is one problem:
In the heading lines of the table (between toprule and midrule) there is text and variables and units which regularly produce errors when columns are formatted with S[...] so that I have to manually enclose every one of those texts with round brackets }.
I wonder: Is there a way to exclude a whole tabular line from the S-column formatting and mark it as "text" (as if every cell would be written in "{}")?

siunitx; thanks! I don't mind closing text with braces in tables with a manageable number of cells. – Ébe Isaac Sep 17 '18 at 07:28