Header/Version: M45-QB1=
Data: slot-name
Delimiter: ,
Deflated and Base64 encoded:
https://lua-api.factorio.com/latest/classes/LuaHelpers.html#encode_string
Test string: eNqtULFuQzEI/CEzVGrHLt079BOwH3VQMFjAi/r5ddIoUTKX4dAdAt3x+foGXx8v75FEAu1AkSXSHDtBoh4L/UynCEhHjWmeUEnyJu+6kXe31R8HMYUzycs3RgJrkJ+ZmHY44Nra7mLd5XhnMVAESKilc4NpQmXQxvt4Eiv3JyX2GonJpmXypAtAGvwZLI4sF4DgrigFW/KJYLqdeOW45nerdk56dSI4Zmmm67ImNBuVFdeLyn/XL5Vihso=
253 bytes for 20 items.
Visual:
Example code: https://github.com/M45-Science/SoftMod/blob/Main/quickbar.lua