[allowClear] property binding

[rpdyer]

With the code below, from https://valor-software.com/ng2-select, property binding with square brackets is used to bind the "items" and "disabled" properties to member fields of the same name. So shouldn't allowClear be used below without square brackets since it is obviously binding to the value "true" rather than to a member field named "true". In my code I tried to use square brackets to bind the allowClear property to a boolean member field in my component, and it fails to work correctly. Does allowClear always have to be bound with square brackets, and always to the "true" and "false" literals?

<ng-select [allowClear]="true" [items]="items" [disabled]="disabled" (data)="refreshValue($event)" (selected)="selected($event)" (removed)="removed($event)" (typed)="typed($event)" placeholder="No city selected">

[MIAOMIAOUP]

allowClear (?boolean=false) (not yet supported) - Set to true to allow the selection to be cleared. This option only applies to single-value inputs.