What the file contains
A Litematic stores region dimensions, a block-state palette, packed block states, metadata, and an explicit data version in compressed NBT format.
Local generation
Blockform creates the file in your browser. The plan is not uploaded. Select horizontal or vertical orientation and a material before exporting.
Compatibility note
Import the file with a current stable Litematica release and verify orientation and palette in a test world before using it in an important build. Game and mod formats can change.