diff --git a/doc/src/manual/variables.md b/doc/src/manual/variables.md
index 0aaa3b6c5d8ca6..e7b2899dd931bc 100644
--- a/doc/src/manual/variables.md
+++ b/doc/src/manual/variables.md
@@ -106,6 +106,9 @@ will reassign it. Most of the Unicode infix operators (in category Sm), such as
 as infix operators and are available for user-defined methods (e.g. you can use `const ⊗ = kron`
 to define `⊗` as an infix Kronecker product).  Operators can also be suffixed with modifying marks,
 primes, and sub/superscripts, e.g. `+̂ₐ″` is parsed as an infix operator with the same precedence as `+`.
+A space is required between an operator that ends with a subscript/superscript letter and a subsequent
+variable name. For example, if `+ᵃ` is an operator, then `+ᵃx` must be written as `+ᵃ x` to distinguish
+it from `+ ᵃx` where `ᵃx` is the variable name.
 
 The only explicitly disallowed names for variables are the names of the built-in [Keywords](@ref):