* Schematic representation of merge (rectangular data)
preserve

clear

input x key str4 id
1 90 1
6 90 1
1 85 2
6 85 2
1 80 3
6 80 3
1 75 4
6 75 4
1 70 5
6 70 5
1 65 etc.
6 65 etc.
end

gen keybig = key if x == 1
gen keysmall = key if x == 6
separate key if id ~= "etc." , by(id)
local opt "connect(l) ms(i) clstyle(p1) legend(off)"
twoway  ///
   (scatter keybig keysmall x, ms(i i) mlabel(id id) mlabpos(9 3))  /// The keys
   (scatteri   0 2 100 2, `opt' clstyle(p2)) /// The dashed lines 
   (scatteri   0 7 100 7, `opt' clstyle(p2)) /// 
   (scatteri   0 0 100 0, `opt' ) /// The boxes
   (scatteri 100 0 100 4, `opt' ) ///
   (scatteri 100 4   0 4, `opt' ) ///
   (scatteri   0 4   0 0, `opt' ) ///
   (scatteri   0 5 100 5, `opt' ) ///
   (scatteri 100 5 100 9, `opt' ) ///
   (scatteri 100 9   0 9, `opt' ) ///
   (scatteri   0 9   0 5, `opt' ) ///
   (line key1-key5 x, c(L L L L L) clstyle(p1 p1 p1 p1 p1)) /// The key-connections 
   , text(95 1 "key") text(95 3 "var 1") ///  The Chart-Junk
     text(95 6 "key") text(95 8 "var 2") ///
     text(100 2 "file 1", placement(n)) text(100  7 "file 2", placement(n)) ///
     plotregion(style(none))  /// 
     xscale(off) yscale(off) ylabel(, nogrid) scheme(s1mono)

restore
exit