Clarify intermediate update (#1886)

docs/2_3_common_states.adoc

@@ -98,7 +98,6 @@ Only in this case, <<fmi3DoStep>> may return with <<earlyReturn,`earlyReturn = f
 This set may be empty (<<nRequiredIntermediateVariables>> = 0) when the simulation algorithm does not intend to use intermediate update.
 Only the variables in <<requiredIntermediateVariables>> may be accessed by the simulation algorithm using <<get-and-set-variable-values,`fmi3Set{VariableType}`>> and <<get-and-set-variable-values,`fmi3Get{VariableType}`>> during <<IntermediateUpdateMode>>.
 All variables referenced in this set must be marked with the attribute <<intermediateUpdate,`intermediateUpdate = "true"`>> in <<modelDescription.xml>>.
-For Co-Simulation, these intermediate variables must be continuous-time variables.
 
 * [[nRequiredIntermediateVariables,`nRequiredIntermediateVariables`]] `nRequiredIntermediateVariables` gives the number of entries in <<requiredIntermediateVariables>>.
 If <<nRequiredIntermediateVariables>> is zero <<requiredIntermediateVariables>> is not defined.

docs/2_4_common_schema.adoc

@@ -1026,11 +1026,12 @@ _Therefore, such an <<input>> should not appear in an algebraic loop.]_
 |
 [[intermediateUpdate,`intermediateUpdate`]]
 If this boolean attribute is `true`, the variable can be accessed in <<IntermediateUpdateMode>>.
-Variables with <<causality>> = <<parameter>> must not be marked with <<intermediateUpdate,`intermediateUpdate = true`>>.
+Only continuous-time variables can have <<intermediateUpdate,`intermediateUpdate = true`>>.
+The default value of this attribute is `false`.
 
-This attribute is ignored in Model Exchange and Scheduled Execution.
 Variables of type <<Clock>> must not have the <<intermediateUpdate>> attribute.
-The default value of this attribute is `false`.
+
+This attribute is ignored in Model Exchange and Scheduled Execution.
 
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