Space between 2 headers

[Kamal]

I have the following:

\score {
{ c }
\header {
  title = "Title1"
}
\layout {
  indent = 0.0
}
}
\score {
{ c }
\header {
  title = "Title2"
}
\layout {
  indent = 0.0
}
}

\version "2.8.6"

What is the property which sets the vertical length between score1 &
score2 (indicated by a cross on the attached pic)?

I used:
\paper{
printallheaders=##t
annotate-spacing = ##t
}
But it doesn't show clearly what is the property name.

header.png
Description: PNG image