Editing : Fades and Crossfades : Creating a Crossfade : Pre and Post Crossfade Selections

Pre and Post Crossfade Selections
By making a selection that begins or ends precisely on the border of two clips, you can create “pre” or “post” crossfades. Use the Tab key to place the insertion point at the exact beginning or end of a clip.
To create a pre- or post-crossfade:
1 With the Selector tool, click in the track that contains the clips you want to crossfade.
2 Do one of the following:
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– or – 
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Press Control+Tab (Windows) or Option+Tab (Mac) to move back to the previous clip boundary.
3 Extend the selection as follows:
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Shift-drag to adjust your selection, or press Shift+Tab to extend the selection forward to the next clip boundary.
– or – 
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Press Control+Shift+Tab (Windows) or Option+Shift+Tab (Mac) to extend the selection back to the previous clip boundary.
4 Do one of the following:
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Choose Edit > Fades > Create.
– or – 
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5 Select a fade type and click OK.