The @ format?

[Frepo]

I noticed in e.g. painting.json the following:

shapebytype: {
        "@painting-(lastday|sodhouse)-.*": { base: "block/wood/painting2x1", rotateYByType: { "*-north": 180, "*-east": 90, "*-south": 0, "*-west": 270 } },
        "*": { base: "block/wood/painting1x1", rotateYByType: { "*-north": 180, "*-east": 90, "*-south": 0, "*-west": 270 } }
 },

is this the same as:

shapebytype: {
        "painting-sodhouse-.*": { base: "block/wood/painting2x1", rotateYByType: { "*-north": 180, "*-east": 90, "*-south": 0, "*-west": 270 } },
        "painting-lastday-.*": { base: "block/wood/painting2x1", rotateYByType: { "*-north": 180, "*-east": 90, "*-south": 0, "*-west": 270 } },
        "*": { base: "block/wood/painting1x1", rotateYByType: { "*-north": 180, "*-east": 90, "*-south": 0, "*-west": 270 } }
 },

or is there anything more to it (other than being a convenient way of reducing the number of lines)?

[Melchior]

That is a Regular-Expression (like) special use character. It alters how code expansion/matching works.
More info in the Discord modding channels... ( https://discord.com/invite/CkJjdrB )

https://wiki.vintagestory.at/index.php/Modding:Item_Json_Properties#p_variantgroups