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.
Shorthand notation for a few special European characters has also been added (Table 4.8):
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 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 Eötvös
10@+-3 @Angstr@om= 10 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.