Lava is an experimental, visual object-oriented, interpreter-based programming language with an associated programming environment (Lava Programming Environment or LavaPE) that uses structure editors instead of text editors. Only comments, constants, and new identifiers may be entered as text. Declarations are represented in LavaPE as tree structures whose subtrees may be collapsed or expanded. The properties of the declared Lava entities can be edited through pop-up dialogs. Further characteristic properties of Lava and LavaPE include the following: