Problem with nested tables

[Andrea Albarelli]

I'm a newbie, so maybe this problem is trivial :

I have tho nested tables and i don't want to have the blank space above the
begin of the nested table in the first row of the main table.

Sorry if it's a stupid question ...

The faulty source is :

@SysInclude { tbl }
@SysInclude { picture }
@Illustration {
@Tbl
   rule { yes }
   aformat { @StartHSpan @Cell indent { ctr } A | @HSpan }
   bformat { @Cell A | @Cell B }
   ab { 0p }
 {
 @Rowa
   A {
@Tbl
   rule { yes }
   ap { lightgrey }
   aformat { @Cell indent { ctr } A }
 {
 @Rowa
   A { padova } m { 4p }
 }
 } m { 0p } h { 0p }
 @Rowb
   A {  }
   B {  }
 @Rowa
   A {  }
 }
}