You can mark and objects using . to keep track of objects you still need to work with. This is called the selection.

PCC2 manages eight layers of selections, called "A" to "H". At almost any place, you can switch selection layers using Alt‐Left and Alt‐Right, and you can invoke the Selection Manager using Alt‐.. You can use this, for example, to keep track of the planets you're working with on one layer, and visualize search results on the others.

The following functions are available on the Selection Manager:

  • D: Clear one layer (unselect all objects). With Ctrl: clear all layers.
  • I: Invert one layer. With Ctrl: invert all layers.
  • C: Copy/compute the current layer from an expression, see below.
  • S: Save current selection layer. With Ctrl: save all layers.
  • L: Load one or all selection layers from a saved file.
  • M: Merge one or all selection. Like L, but adds to the previous selection instead of replacing it.
  • F7: List objects on current layer. Activates the layer and shows it in the Search dialog.
  • Enter: Select new current layer and close Selection Manager.
  • ESC: Close selection manager.

Selection Expressions

You can compute a selection layer's content from other layers' content. For example, you can merge two layers using an expression such as A or B: the result will be a selection that contains all objects that were in A or B. In the simplest form, the selection expression contains just a layer name, such as D, which just copies a layer.

The following contains possible selection expressions in order of increasing precedence.

  • Lowest priority:
    a Or b
    Logical Or: yields all objects that are in a or b.
    a + b
    Same as a Or b.
    a Xor b
    Logical Exclusive-or: yields all objects that are in a or b, but not in both.
    a - b
    Logical Subtraction: yields all objects that are in a, but not in b.
  • Medium priority:
    a And b
    Logical And: yields all objects that are in a and in b.
    a * b
    Same as a And b.
  • Highest priority (unary operators):
    Not a
    Logical Negation: yields all objects that are not in a.
    -a
    Same as Not a.
    (a)
    Parentheses: yields a.
    P(a), PLANETS(a)
    Yields all the planets contained in a.
    S(a), SHIPS(a)
    Yields all the ships contained in a.
    CURRENT
    Yields the current selection.
    A, B, ..., H
    Yields the contents of the specified layer.
    P, PLANETS
    Yields the list of all planets.
    S, SHIPS
    Yields the list of all ships.
    0
    Yields an empty selection.
    1
    Yields the full selection containing all objects.

Reference

Keys:
Alt‐. from almost everywhere
Related command:
UI.SelectionManager, SelectionExec