::: Yes, one needs H-bonds to define beta-sheet; and a beta-strand without beta-sheet is simply an extended conformation (just as polyPro helix, another regular structure, although it might be not "secondary").  I also agree that beta-sheet topology belongs to tertiary structure and "it doesn't influence secondary structure", i.e. it does not influence which residues are included in the beta-strands, it only influences the structure of the beta-sheet.  However, the beta-sheet and beta-strand are certainly two different things; it is too bad if they are interchangeable in textbooks or Wikipedia.  I do not want tilting at windmills as you say. That was simply a comment.