Why do my corner points have curves?

Question

Here's the problem:
I select the Pen tool in InDesign CS in Document A. I click at a certain spot, move and click again, move and click again. The resultant two-segment line has a curve at the corner point. Nothing I do can remove that curve.
When I try exactly the same thing in a new document, Document B, the curve is not there.
What settings have I got in Document A that causes this and how do I change those settings?
Document A can be downloaded here:
http://www.mediafire.com/?0njedxovgyn
It's blank, except for the three corner points.

Answer 1

> Now that brings up another point: at no stage did I select 'rounded corners' when using the Pen tool, though I have used rounded corners for image frames. Doesn't seem quite right to me that an option applied to one type of object should automatically be applied to every other type. So I have a question:
> Is it possible, at some stage during the use of a tool, to force it to its default settings? For example, you can force a Paragraph Style to its default settings (and remove any overrides) by holding 'Option' when clicking on the style. Can a similar method be used with other tools?
You're making a common mistake. The Object Styles and default settings for objects are not applied to
i tools.
They are applied to
i objects.
The Pen tool does not create Pen objects. It creates objects that are styled with the Basic Graphic Frame object style.
There are six tools that use the Basic Graphic Frame object style as the default style for the objects they create: Pen tool, Pencil tool, Rectangle tool, Ellipse tool, Polygon tool, and Line tool.
Therefore any change to the default Basic Graphic Frame style will apply to all objects created with these tools. (It can be confusing to realize that the lines created with the Line tool have rounded corners if Corner Effects have been applied to the style. Especially since there are no corner points in the lines to display the corner effects.
Furthermore, there is a big confusion as to what these objects are. The name of the default style for these objects is Basic Graphic Frame.
b But these objects are not Graphic frames. They are Unassigned frames.
This is the big confusion for me when I teach as the word "Graphic" in the style name is not applied to Graphic frames.
In fact, the objects created by the Rectangle
i Frame
tool, the Ellipse
i Frame
tool, and the Polygon
i Frame
tool, are all created with the None Object Style attribute.
The default for the None setting for those tools is always Fill: None, Stroke: None. And while it is possible to apply a local override to the None style, you can't modify it (as far as I know) to be different.
But remember, it is those three tools that create
i Graphic
frames.
b You would think that Graphic frames would have the Basic Graphic Frame object style applied.
But you would be wrong.