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.