commit 8ed89a1e816d5a1c01f2139b64485fdfb9b62318
Author: Jordon Moss <mossj32@gmail.com>
Date:   Sat Apr 16 05:52:27 2022 -0700

    When loading new art files, blanks no longer erase existing tiles, allowing "inserting" new tiles, or essentially stacking them.

See https://voidpoint.io/terminx/eduke32 for more details.