diff --git a/schemas/IndicatorSet.yaml b/schemas/IndicatorSet.yaml
index 930f75f..c1eb890 100644
--- a/schemas/IndicatorSet.yaml
+++ b/schemas/IndicatorSet.yaml
@@ -44,6 +44,14 @@ properties:
           description: In dutch, plain text formatted; should fit on one line.
           type: string
           example: Populatie
+        htmlDescription:
+          description: In dutch, HTML formatted; if present, contains details on how this value is measured (in more readable, less technical terms than `htmlDetail`.
+          type: string
+          example: Patiënten met ≥ 1 voorschrift(en) long acting beta-2 agonists (LABA) of long acting muscarine antagonists (LAMA) in de afgelopen 12 maanden
+        htmlDetail:
+          description: In dutch, HTML formatted; if present, contains specific details on how this value is measured (for example, contains information about which NHG bepaling codes are used).
+          type: string
+          example: LAMA (<code>R03BB</code> (04, 05, 06 of 07)) of LABA (<code>R03AC</code> (12, 13, 18 of 19))
         indicatorGroups:
           description: |-
             A chapter contains 1 or more indicator groups. An indicator group is an array of indicators which should