I've got this:

#+tblname: mydata
|     -2 | 0 |
| -0.015 | 0 |
|        |   |
|  0.015 | 1 |
|      2 | 1 |

##+begin_src gnuplot :var data=mydata :exports results :file images/gap1.png
#+begin_src gnuplot :var data=mydata :results output :file images/gap1.png
reset
set terminal png size 350,262
set border linewidth 1.5
# set style line 1 lc rgb '#0060ad' lt 1 lw 2 pt 6 ps 1.25 # --- blue
set style line 1 lc rgb '#0060ad' lt 1 lw 2 # --- blue
set data missing

unset key

set ytics 1
set tics scale 0.75

set xrange [-2:2]
set yrange [-0.5:1.5]
set xzeroaxis linetype 2 linewidth 1
set yzeroaxis linetype 2 linewidth 1
set tics scale 0.75
set xtics 1
set ytics 0.5

# Defining a step function
#s(x) = x<0 ? 0.0 : 1.0

plot data with lines ls 1
#+end_src

which works fine producing exactly the image I want. However, I don't
really need the table showing up on an export (to html at the moment). Is
there a way to suppress the table `mydata` from being shown?

LB