Font substitution and linking #3

Anyway, at the end of last month, M.W. Grossman asked me the following question:

An interesting problem, one that is rooted in the issues of Han unification that I have discussed previously.

What it comes down to is that there are many characters which can have four different possible looks:

• Japanese will default to using MS UI Gothic (fallback to PMingLIU, then SimSun, then Gulim)
• Korean will default to using Gulim (fallback to PMingLiu, then MS UI Gothic, then SimSun)
• Simplified Chinese will default to using SimSun (fallback to PMingLiu, then MS UI Gothic, then Batang)
• Traditional Chinese will default to using PMingLiu (fallback to SimSun, then MS Mincho, then Batang)

Now there are nuances like when you install HKSCS stuff for Hong Kong or GB18030 stuff for China and other random things that I'll talk some other time. But the above four are the msin font linking rules.

The change depends on the setting of the NLS default system locale (meaning of course that this is a setting that is not just for non-Unicode programs!). It affects the behavior of several things, according to the rules spelled out above for each group -- linking to the fonts in that given order:

• The preferred font for each group (for EA system locales)
• Lucida Sans Unicode
• Microsoft Sans Serif (not MS Sans Serif!)
• Tahoma

This is the most common Windows XP/Server 2003 list, it changes a bit between versions depending on default UI fonts -- mainly by adding new entries but leaving the old ones intact. Your mileage may vary, especially as some third party font installs will often try to modify these settings, often with success but occasionally with messed up registry setttings....

Now I have gone on for quite a while here, without explaining what this linking does. The essential task performed is to give the operating system a list of fonts to look in and an order to look in them when the requested character cannot be found in the original font. Given that both Han unification and typographic traditions will dictate a specific look, feel, and glyph design to each font, the list is chosen so that a cirrect choice for the default system locale is most likely to give an intuitive look to the text that is shown on Windows.

The actual mapping is found in the registry; it is seen in the values under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontLink\SystemLink. A change requires a new windowstation, which for all shipping versions of Windows means either a reboot (which the default system locale requires anyway) or a new Terminal Services session.

Of course, the user can always override these things if he wants to by explicitly choosing the 'right' default system locale; the developer can override these things if she needs to p.r.n. by choosing the fonts to use, explicitly. But in both cases, the user and the developer will often just use the default.

But if you are a developer who is wanting to influence the selection here, PLEASE consider explicitly choosing a font rather than changing a system wide setting....

This post brought to you by "一" (U+4e00, a.k.a. the first CJK Unified Idedograph)
One of the few ideographs used by all languages that use Han/Kanji/Hanja but that does not tend to vary too much in style....