Old-fashioned character sets such as
ASCII and
ISO-8859-1 do indeed lack the two
characters necessary for Welsh:
W with a
circumflex accent and
Y with a
circumflex accent. While
ISO-8859-14 does support them, its use is quite rare.
Yet again, Unicode comes to the rescue:
Ŵ Ŵ U+0174 LATIN CAPITAL LETTER W WITH CIRCUMFLEX
ŵ ŵ U+0175 LATIN SMALL LETTER W WITH CIRCUMFLEX
Ŷ Ŷ U+0176 LATIN CAPITAL LETTER Y WITH CIRCUMFLEX
ŷ ŷ U+0177 LATIN SMALL LETTER Y WITH CIRCUMFLEX
Unicode also offers an alternative concept of
combining characters:
̂ U+0302 COMBINING CIRCUMFLEX ACCENT
Combining characters are generally
diacritics which, when following any character, combine with it in a single character space. Thus:
Ŵ = Ŵ
ŵ = ŵ
Ŷ = Ŷ
ŷ = ŷ
As usual with Unicode, older browsers such as Netscape 4 don't support many characters. Get rid of your '90s browser and update to Mozilla or Internet Explorer.
You also need a font which supports these characters but modern operating systems generally support all but the rarest characters.