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4.16 Character escape sequences

For annotation labels or textstrings plotted with pstext, GMT provides several escape sequences that allow the user to temporarily switch to the symbol font, turn on sub- or superscript, etc., within words. These conditions are toggled on/off by the escape sequence @x, where x can be one of several types. The escape sequences recognized in GMT are listed in Table 4.7.


Table 4.7: GMT text escape sequences.
Code Effect
@~ Turns symbol font on or off
@%fontno% Switches to another font; @%% resets to previous font
@+ Turns superscript on or off
@- Turns subscript on or off
@# Turns small caps on or off
@! Creates one composite character of the next two characters
@@ Prints the @ sign itself


Shorthand notation for a few special European characters has also been added (Table 4.8):


Table 4.8: Shortcuts for some European characters.
Code Effect Code Effect
@E Æ @e æ
@O Ø @o ø
@A Å @a å
@C Ç @c ç
@N Ñ @n ñ
@U Ü @u ü
@s ß    


PostScript fonts used in GMT may be re-encoded to include several accented characters used in many European languages. To access these, you must specify the full octal code $\backslash$xxx allowed for your choice of character encodings determined by the CHAR_ENCODING setting described in the gmtdefaults man page. Only the special characters belonging to a particular encoding will be available. Many characters not directly available by using single octal codes may be constructed with the composite character mechanism @!.

Some examples of escape sequences and embedded octal codes in GMT strings using the Standard+ encoding:


		2@~p@~r@+2@+h@-0@- E\363tv\363s 		 = 		 2$\pi r^2h_0$ Eötvös 

10@+-3 @Angstr@om = 10$^{-3}$ Ångstrøm
Se@nor Gar@con = Señor Garçon
M@!\305anoa stra@se = Manoa straße
A@\#cceleration@\# (ms@+-2@+) = ACCELERATION (MS)

The option in pstext to draw a rectangle surrounding the text will not work for strings with escape sequences. A chart of characters and their octal codes is given in Appendix F.


next up previous contents index
Next: 4.17 Embedded grdfile format Up: 4. General features Previous: 4.15 Color palette tables   Contents   Index
Paul Wessel 2004-10-01