diff --git a/doc/src/sgml/json.sgml b/doc/src/sgml/json.sgml
index fae13743984..b8246badda9 100644
--- a/doc/src/sgml/json.sgml
+++ b/doc/src/sgml/json.sgml
@@ -836,17 +836,22 @@ SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @> '{"tags": ["qu
[subscript, ...]
-
- [subscript to last]
-
- Array element accessor. The provided numeric subscripts return the
- corresponding array elements. The first element in an array is
- accessed with [0]. The last keyword denotes
- the last subscript in an array and can be used to handle arrays
- of unknown length.
+ Array element accessor. subscript
+ might be given in two forms: expr
+ or lower_expr to upper_expr.
+ The first form specifies single array element by its index. The second
+ form specified array slice by the range of indexes. Zero index
+ corresponds to the first array element.
+
+
+ Expression inside subscript may consititue an integer,
+ numeric expression or any other jsonpath expression
+ returning single numeric value. The last keyword
+ can be used in the expression denoting the last subscript in an array.
+ That's helpful for handling arrays of unknown length.