Selection of a text based on the passed value

Give the displayvalue() function a try.

a!localVariables(
  local!selectedtype: "IM",
  local!myDictionary: {
    { cText: "Internal Memo", typeId: "IM" },
    { cText: "External Memo", typeId: "EM" },
    { cText: "Correspondence", typeId: "CP" }
  },
  displayvalue(
    local!selectedtype,
    local!myDictionary.typeId,
    local!myDictionary.cText,
    null
  )
)