Re: ct, fj and blackletter ligatures

From: John Hudson (
Date: Sat Nov 02 2002 - 17:44:43 EST

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    At 15:53 11/2/2002, Thomas Lotze wrote:

    > > Ironically, the sequence c+ZWJ+t is more likely *not* to display as a
    > > ligature, since the ZWJ interferes with the sequence recognised by the
    > > font lookups.
    >Does this mean that it is indeed common practice to replace every last
    >occurrence of a character sequence be the corresponding ligature with
    >these fonts? At least in the german language, this would be desastrous:
    >there are many cases where character sequences occur but the ligature is
    >not allowed, e.g. if two words are combined into one, the last letter of
    >the first one does not form a ligature with the first letter of the
    >second even if such a ligature exists. Don't know about other languages,

    German is indeed a special case, and there are various ideas for how best
    to handle German ligation. Clearly, inserting ZWJ where one wanted ligation
    -- or, perhaps, ZWNJ where one didn't want it -- is an option. Using ZWNJ
    is probably a better solution, if one went this route, since it would work
    with existing ligature implementations in OpenType, AAT and Graphite: i.e.
    it would prevent ligatures from forming. However, expecting German users to
    manually enter ZWJ or ZWNJ in their documents seems highly impractical, so
    an automated dictionary-driven system seems to be required. This is getting
    outside my area of expertise.

    For other languages, it is typical for a set of standard ligatures (usually
    those involving f followed by an ascending form: fb ffb ff fh ffh fi ffi fj
    ffj fk ffk fl ffl) to be on by default because these ligatures are not
    merely stylistic but preserve word shape integrity by reducing white space
    between the letters while avoiding distracting collisions. The well known
    exception to this is found in the typography of those Turkic languages that
    employ a dotless as well as a dotted i: for these languages fi and ffi
    ligature formation needs to be supressed, or special ligatures need to be
    provided that do not remove the dot of the i. OpenType includes a Language
    System tag that allows a layout feature such as Standard Ligatures <liga>
    to have different lookups for different writing systems.

    Stylistic ligatures such as ct and st, are typically handled in a separate
    feature, which is not on by default. Obviously in fraktur fonts the
    designer might decide to include ligatures like ch and ck in the standard set.

    John Hudson

    Tiro Typeworks
    Vancouver, BC

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