Merge pull request #585 from control-toolbox/jbcaillau-patch-1

Update manual-abstract.md

Author: ocots

docs/src/manual-abstract.md

@@ -471,7 +471,7 @@ end
 :( $a = $e1 )
 ```
 
-The single `=` symbol is used to define not a constraint but an alias, that is a purely syntactic replacement. There are some automatic aliases, *e.g.* `x₁` for `x[1]` if `x` is the state, and we have also seen that the user can define her own aliases when declaring the [variable](@ref manual-abstract-variable), [state](@ref manual-abstract-state) and [control](@ref manual-abstract-control). Arbitrary aliases can be further defined, as below (compare with previous examples in the [dynamics](@ref manual-abstract-dynamics) section):
+The single `=` symbol is used to define not a constraint but an alias, that is a purely syntactic replacement. There are some automatic aliases, *e.g.* `x₁` and `x1` for `x[1]` if `x` is the state (same for variable and control, for indices comprised between 1 and 9), and we have also seen that the user can define her own aliases when declaring the [variable](@ref manual-abstract-variable), [state](@ref manual-abstract-state) and [control](@ref manual-abstract-control). Arbitrary aliases can be further defined, as below (compare with previous examples in the [dynamics](@ref manual-abstract-dynamics) section):
 
 ```julia
 @def begin