The flyer holds the bar with their hands shoulder-width apart. Their arms are straight and parallel.
This is by far the most common way to hold the bar and should be considered the 'default' in case no other grip is mentioned. Examples of tricks that use this grip are: Knee Hang, Layout.
Note that the image shows the flyer with their thumbs under the bar (around). This is the most common way, however some schools prefer the thumbs to be over the bar.
You can find out more about this trick in my books:
IMAGE CREDIT: Diana