Editing Precomposed character (section)

== Comparing precomposed and decomposed characters ==

In the following example, there is a common [[Swedish language|Swedish]] surname Åström written in the two alternative methods, the first one with a precomposed ''[[Å]]'' (U+00C5) and ''[[ö]]'' (U+00F6), and the second one using a decomposed base letter ''[[A]]'' (U+0041) with a combining [[ring above]] (U+030A) and an ''[[o]]'' (U+006F) with a combining [[trema (diacritic)|diaeresis]] (U+0308).

#'''<span style="font-size:125%;"><span style="color:green">Å</span>str<span style="color:green">ö</span>m</span>''' (<span style="color:green">U+00C5</span> U+0073 U+0074 U+0072 <span style="color:green">U+00F6</span> U+006D)
#<span style="color:DeepSkyBlue;"><span style="font-size:125%;">'''A&#x030A;stro&#x0308;m'''</span> (U+0041 <span style="color:darkorange">U+030A</span> U+0073 U+0074 U+0072 U+006F <span style="color:darkorange">U+0308</span> U+006D)</span>

Except for the different colors, the two solutions are equivalent and should render identically. In practice, however, some Unicode implementations still have difficulties with decomposed characters. In the worst case, combining diacritics may be disregarded or rendered as unrecognized characters after their base letters, as they are not included in all [[font]]s. To overcome the problems, some applications may simply attempt to replace the decomposed characters with the equivalent precomposed characters.

With an incomplete font, however, precomposed characters may also be problematic – especially if they are more exotic, as in the following example (showing the reconstructed [[Proto-Indo-European language|Proto-Indo-European]] word for "dog"):

#'''<span style="font-size:125%;"><span style="color:green">ḱṷṓ</span>n</span>''' (<span style="color:green">U+1E31 U+1E77 U+1E53</span> U+006E)
#'''<span style="font-size:125%;">k&#x0301;u&#x032D;o&#x0304;&#x0301;n</span>''' (U+006B <span style="color:darkorange">U+0301</span> U+0075 <span style="color:darkorange">U+032D</span> U+006F <span style="color:darkorange">U+0304 U+0301</span> U+006E)

In some situations, the precomposed green [[k]], [[u]] and [[o]] with diacritics may render as [[Mojibake|unrecognized characters]], or their [[typography|typographical]] appearance may be very different from the final letter [[n]] with no diacritic. On the second line, the base letters should at least render correctly even if the combining diacritics could not be recognized.

[[OpenType]] has the ''ccmp'' "feature tag" to define glyphs that are compositions or decompositions involving combining characters.