+' sign means `read another line of keywords'. Note the space
before the `+' sign. Since `+' is a keyword, it must be preceeded by a
space. A ` +' on line 1 would mean that a second line of keywords should
be read in. If that second line contains a ` +',
then a third line of
keywords will be read in. Regardless of whether a second or a third line
of keywords is read in, the next two lines would be description lines.
Example of ` +' option
RESTART T=4D FORCE OPEN(2,2) SHIFT=20 PM3 +
SCFCRT=1.D-8 DEBUG + ISOTOPE FMAT ECHO singlet ROOT=3
THERMO(300,400,1) ROT=3
Example of data set with three lines of keywords. Note: There are two lines of description, this and the previous line.