Compilation Units 

Compilation units are written by calling inPackage(sym|"p") or withoutPackage on BLOCK(...):

BLOCK(
  OBJECTDEF("M")
) inPackage("p")

This prints as:

package p

object M

BLOCK(
  OBJECTDEF("M1"),
  OBJECTDEF("M2")
) withoutPackage

This prints as:

object M1

object M2