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Diffstat (limited to 'doc/expert/pre_unde')
| -rw-r--r-- | doc/expert/pre_unde | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/doc/expert/pre_unde b/doc/expert/pre_unde new file mode 100644 index 0000000..1261449 --- /dev/null +++ b/doc/expert/pre_unde @@ -0,0 +1,30 @@ +@Section + @Tag { underline } + @Title { "@Underline" } +@Begin +@PP +underline.sym @Index { @@Underline symbol } +The @@Underline symbol underlines its right parameter, but only if that +parameter is a word or a paragraph: +@ID @Code "We @Underline { really do } mean this." +produces +@ID { We @Underline { really do } mean this. } +It is not possible to underline an arbitrary object using this symbol; +the @@Underline symbol will be ignored if this is attempted. +@PP +It is very easy to @I define a symbol which will underline an arbitrary +object, using the @@Graphic symbol. This raises the question of why +@@Underline is needed at all. The answer is that @@Underline has two +properties that distinguish it from symbols based on @@Graphic. +@PP +First, when @@Underline both contains a paragraph and is used within a +paragraph, as in the example above, the inner and outer paragraphs are +merged into one, permitting the underlined text to break over several +lines. This is how the @@Font symbol works too, but symbols based on +@@Graphic do not permit this merging. +@PP +Second, Adobe font files specify the correct position and thickness of +underlining for each font, and the @@Underline symbol follows these +specifications. The font used is the font of the first object underlined, +if it is a simple word, or else the font of the enclosing paragraph. +@End @Section |