How to add element condition (Legacy)
Every template element can have a condition. Condition is defined with if attribute. When if attribute value is true the element will be show in the document otherwise the element and all child elements will be removed from the generated document. If attribute is an expression i.e. value is determined by evaluating the EL. Typically EL is Salesforce field reference.
Also content attribute can have condition with two options. Notation is: if value ? then : else
More info on expression language
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