Prior to my migrating from RHEL 5.5 to 6.0, when I used characters U+22b3, U+22b5, U+227b (‘≻’), U+227f (‘≿’), and U+2280 (‘⊀’) in formulae coded within OpenOffice Math (the formula editor) of OpenOffice 3.2.1, the document displayed these when viewed in OpenOffice, and an exported PDF displayed these when viewed with Acrobat readers.

Now, when the very same version of OpenOffice is used in RHEL 6.0, these character becomes invisible both in .ODTs and in .PDFs. This problem obtains, in fact, whether I use the distribution of OpenOffice supplied by OpenOffice.org or that provided by Red Hat.

I don't know whether this problem obtains from changes in fontconfig, from a change in the installed set of fonts, or from some other source.

That documentation and discussion which I have encountered of fontconfig does not clearly distinguish character-wise fallback from wholesale substitution of one font for another, let alone provide a clear guide as to how to diagnose my present problem.