Saving

What to keep#

The Save dialog's What to keep choice decides what goes into the file. None of it changes the map you have open, only the file being written.

Choice	What the file holds
Everything	Every section and archive member. The file opens in any editor with nothing lost.
Smallest that plays	All five ticks below, and StarEdit's PKWARE compression with encryption. The map plays the same; an editor opening it later has less to work with.
Custom	The ticks you choose.

The five ticks under Custom:

Leave out terrain editing data: ISOM, TILE and DD2 .
Leave out editor bookkeeping: IVER, IVE2, IOWN, UPUS, SWNM and WAV .
Leave out sections the format reference does not know.
Merge repeated sections into one, by the game's rules.
Drop bytes after the last section.

Each extra archive member also has its own tick in the Archive fold.

What the game reads and what it skips#

The nine sections in the first two ticks are read by editors and skipped by the game. The map plays the same without them. What changes is what an editor can do with the file afterwards:

Without ISOM, the isometric brush has nothing to paint with. The Repair plugin can rebuild the record from the tiles, and does well on terrain that was laid isometrically to begin with.
Without TILE and DD2 , doodads are no longer objects. Their tiles are still in the terrain and their sprites in THG2, but an editor cannot pick one up or restore the ground beneath it.
Without SWNM and WAV , switches lose their names and the Sound Editor its list; the triggers that use them are unaffected.
IOWN, IVER, IVE2 and UPUS are StarEdit's own notes and cost nothing.

Stripping these is what map protectors and "map compressors" have always done. It can be undone only as far as the Repair plugin can rebuild the record, so keep an unstripped copy of any map you are still working on.

The file you replace#

A save that writes over a file keeps what it replaced. The desktop app copies the old file to a .bak beside it (Lagoon.scx to Lagoon.scx.bak). A browser cannot write beside the file, so it keeps the last three versions of each file name in its own storage, listed in File ▸ Previous Versions…. A download replaces nothing, so Firefox and Safari have nothing to keep. While a map has unsaved changes, the editor also keeps a recovery copy of it, offered at the next start if the editor closed without saving.

The user guide covers both: Saving and Recovery copies.