One big challenge for OPAC (On-line Public Access Catalog) was supporting the numerous ancient scripts that British Library scholars use, including historical variations on Greek and Cyrillic, Egyptian hieroglyphs, and Hebrew and Arabic (which read from right to left). They don't include the thousands of Chinese and Japanese pictographs. The Oriental Collection will be a separate project.
The Windows-based front end made designing the base characters straightforward, using font-building tools like Fontographer from MacroMedia. Much more difficult was handling the large range of diacritical marks these ancient scripts require: It's just not feasible to create a charact
er set containing all the permitted letter-accent combinations. Instead, OPAC displays compound screen characters, with the diacritical marks overprinted at run time. This required custom coding of the display drivers.
OPAC accepts queries written in scripts from previous centuries, such as this Old Slavonic. It can also mix character sets freely on-screen and needs to support a far wider range of diacritical marks than is required for modern languages.
Flexible C++
Matthew Wilson
My approach to software engineering is far more pragmatic than it
is
theoretical--and no language better exemplifies this than C++.
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Handling Special Character Sets
