Since we no longer have the per user block functionality in core these constants are no longer required.
* Users cannot control whether or not they see this block.
const BLOCK_CUSTOM_FIXED = 0;
* Shows this block by default, but lets individual users hide it.
const BLOCK_CUSTOM_ENABLED = 1;
* Hides this block by default but lets individual users show it.
const BLOCK_CUSTOM_DISABLED = 2;
I'll be adding them into the contrib module for the per user block feature: see