reserve infix `~~~`:50
reserve notation `[` a `][` b:10 `]`

section
local infix `~~~` := eq

#print notation ~~~

local infix `~~~`:50 := eq

#print notation ~~~

local infix `~~~`:100 := eq

infix `~~~`:100 := eq  -- FAIL

#print notation ~~~

local notation `[` a `][`:10 b:20 `]` := a = b

#print notation ][
end

notation `[` a `][`:10 b:20 `]` := a = b -- FAIL

notation `[` a `][` b `]` := a = b
infix `~~~` := eq

#print notation ~~~
#print notation ][