It doesn't have to be a case of "brevis brevians" or "iambic shortening." It could just be the/a natural way to pronounce the word. The Wikipedia article on brevis brevians mentions the pronunciation avĕ rather than avē. >According to Quintilian, avĕ with short -e was the usual pronunciation in his day, the long form being used only by pedantic people. So who's to say that ideŏ isn't a normal pronunciation? If the o is not short, what scansion do you propose? I don't see any better solution than .