diff --git a/LSP.md b/LSP.md
index 83a613e..f3dbb4c 100644
--- a/LSP.md
+++ b/LSP.md
@@ -5,6 +5,8 @@ MaskRay's random complaints about Language Server Protocol
 * VSCode sorts `sortText` case insensitively.
 * VSCode only allows length-one strings in `CompletionRegistrationOptions.triggerCharacters` https://github.com/Microsoft/language-server-protocol/issues/138 (closed) Server developers have to work around that. `CompletionTriggerKind::TriggerCharacter` should extend as well.
 * The order of `textEdit` `additionTextEdits` is not specified.
+* Initially `ParameterInformation.label` was a `string` (this made it difficult to highlight the label),
+  then changed to `string | [number, number]` (https://github.com/microsoft/language-server-protocol/issues/640). Specifying `[start,end)` (`[number, number]`) allows to highlight the label, but then it will not be able to supply a detailed string.
 
 ### Formatting