clarifying empty/not empty

Author: Scoti Dodson

content/concepts/conditions.mdx

@@ -137,25 +137,25 @@ The timestamp operators (`is_timestamp_before`, `is_timestamp_on_or_after`, and
 
 You can use any of the following operators in condition comparisons:
 
-| Operator                   | Description                                                                              |
-| -------------------------- | ---------------------------------------------------------------------------------------- |
-| `equal_to`                 | `==`                                                                                     |
-| `not_equal_to`             | `!=`                                                                                     |
-| `greater_than`             | `>`                                                                                      |
-| `greater_than_or_equal_to` | `>=`                                                                                     |
-| `less_than`                | `<`                                                                                      |
-| `less_than_or_equal_to`    | `<=`                                                                                     |
-| `contains`                 | Checks whether `argument` is in `variable` (works with strings and lists)                |
-| `contains_all`             | Checks whether all `argument` values are present in `variable` (for comparing lists)     |
-| `not_contains`             | Checks whether `argument` is not in `variable` (works with strings and lists)            |
-| `not_contains_all`         | Checks whether all `argument` values are not present in `variable` (for comparing lists) |
-| `empty`                    | Checks whether `variable` is in `["", null, []]`                                         |
-| `not_empty`                | Checks whether `variable` is not in `["", null, []]`                                     |
-| `exists`                   | Checks whether `variable` is provided and has a value that is not `null`                 |
-| `not_exists`               | Checks whether `variable` is not provided or has a `null` value                          |
-| `is_timestamp_before`      | Checks whether `variable` is a timestamp before the `argument` value                     |
-| `is_timestamp_on_or_after` | Checks whether `variable` is a timestamp on or after the `argument` value                |
-| `is_timestamp_between`     | Checks whether `variable` is a timestamp between the `argument`'s start and end values   |
+| Operator                   | Description                                                                                                                                         |
+| -------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `equal_to`                 | `==`                                                                                                                                                |
+| `not_equal_to`             | `!=`                                                                                                                                                |
+| `greater_than`             | `>`                                                                                                                                                 |
+| `greater_than_or_equal_to` | `>=`                                                                                                                                                |
+| `less_than`                | `<`                                                                                                                                                 |
+| `less_than_or_equal_to`    | `<=`                                                                                                                                                |
+| `contains`                 | Checks whether `argument` is in `variable` (works with strings and lists)                                                                           |
+| `contains_all`             | Checks whether all `argument` values are present in `variable` (for comparing lists)                                                                |
+| `not_contains`             | Checks whether `argument` is not in `variable` (works with strings and lists)                                                                       |
+| `not_contains_all`         | Checks whether all `argument` values are not present in `variable` (for comparing lists)                                                            |
+| `empty`                    | Checks whether `variable` is in `["", null, []]`. If the variable is not provided at the path, Knock treats it as empty, so this returns true.      |
+| `not_empty`                | Checks whether `variable` is not in `["", null, []]`. If the variable is not provided at the path, Knock treats it as empty, so this returns false. |
+| `exists`                   | Checks whether `variable` is provided and has a value that is not `null`                                                                            |
+| `not_exists`               | Checks whether `variable` is not provided or has a `null` value                                                                                     |
+| `is_timestamp_before`      | Checks whether `variable` is a timestamp before the `argument` value                                                                                |
+| `is_timestamp_on_or_after` | Checks whether `variable` is a timestamp on or after the `argument` value                                                                           |
+| `is_timestamp_between`     | Checks whether `variable` is a timestamp between the `argument`'s start and end values                                                              |
 
 <Callout
   type="info"