How to make legend

I have following script

gmt begin map
  gmt basemap -R25.5/45.5/34.5/42.5  -JM6i   -U    -B  >> map
  gmt plot eth.csv  -R25.5/45.5/34.5/42.5 -JM6i  -Sc0.05 -G50 -L  -V    -B >> map
 gmt plot blst.csv  -R25.5/45.5/34.5/42.5 -JM6i  -Sc0.1 -G0/0/255 -L  -V    -B >> map
 gmt plot promblast.csv  -R25.5/45.5/34.5/42.5 -JM6i  -Ss0.2 -G128/9/0 -L  -V    -B >> map
gmt end show

How to place legend under ( not on) this map ?
In the legend I wish near each type of symbol on the map
to have texts like this- 1, -2. ?
Is it possible to place few symbols on the one string?
Let say in the first string -Sc0.05 -G50 “-1”, -Sc0.1 -G0/0/255 “-2”
and on the next string -Ss0.2 -G128/9/0 “-3”

I just tested a work around, so my suggestion is

  1. use -l"-1" etc. in each plot command to prepare the legend. The meaning of -L I don’t know. The “>> map” you don’t need in modern style of gmt6.1. Then add the legend command:
    gmt legend -Dx0c/-2c+jTL+o0.5 -Fi+gwhite+pthick
    to place the legend 2 cm below the plot with the box oriented 0.5 cm away from that point identified as top/left corner. See also Example 3 in the galery.