True if the name for the specified trendline is generated automatically from the trendline type and series index ("Poly. (Series 1)", for example). Setting the trendline’s Caption property sets this property to False. Read/write Boolean.
expression.HasAutoCaption
expression Required. An expression that returns a ChTrendline object.
Example
This example sets the caption for the specified trendline caption if the caption is currently set to be generated automatically. Note that SeriesCollection(0) must refer to a series that already has a trendline.
Sub SetCaption()
Dim serZero
Dim trndline
Set serZero = ChartSpace1.Charts(0).SeriesCollection(0)
serZero.Line.Color = "red"
Set trndline = serZero.Trendlines(0)
If trndline.HasAutoCaption Then trndline.Caption = "data trend"
End Sub