All Vietnamese character sets using single byte encoding like VISCII, VPS, ABC, VietWare_F, DHBK1, ISC, etc always suffer display problem with a number of characters, usually upper case letters. A common solution is to use a font pair. Each font is always provided in two versions: regular and capital. The name of the capital font usually has a suffix "H" or "Hoa", the Vietnamese word for capital. For example, "VI Times" and "VI Times H" are a VISCII font pair. The difference between the two versions are as follows:
In the regular version all characters in the font appear exactly as defined by the character set encoding.
In the capital version all characters in the font appear in the capital format even though some of them are defined to be lower case by the character set encoding.
Unfortunately, the capital version of the font is not implemented consistently by all vendors. Some vendors keep the lower case English letters as is and capitalize only Vietnamese accented letters. Others capitalize all letters in the font, both English and Vietnamese alike. Thus to get accurate conversion, WinVNKey needs to know if all letters are capitalized. To this end WinVNKey classifies fonts into three categories:
Regular font: characters appear exactly as defined by the character set encoding.
Capital font: only English lower case letters remain lower case; all other letters are drawn in upper case.
All-Capital font: all English and Vietnamese letters are drawn in upper case.
WinVNKey provides the following dialog to help determine if a font is regular, capital, or all capital. You simply select a font in the combo box and answer two questions.
Look at the characters displayed on the first beginning with the label "(1)". Do you see all upper case or all lower case?
Look at the characters displayed on the second ginning with the label "(2". Do you see all upper case? Or not all characters are upper case?
FYI, characters on the first line are actually lower case English letters. If they appear upper case, the font is likely an all-capital font.
Characters on the second line are actually lower case Vietnamese letters with accent marks. If they appear upper case, the font is likely a capital or all-capital font.
Together, the answers to both lines (1) and (2) will confirm the type of the font. The conclusion is then displayed at the bottom of the dialog.