Spiritually, to be conscious of a line marking the perimeter of an object suggests that we are recognizing a duality – the existence of two things.
To be outlining an idea suggests that we have some basic concepts that are worth exploring.
Psychological / emotional perspective: An outline is usually a brief statement of intent, and with practice in dreams we are often able to formulate such a statement.
An outline document in dreams can symbolize this.
The problem is that when we wake up, unless we are used to recording our dreams, such a statement of intended action can be lost.
Material aspects: An outline in dreams is intended to give emphasis or to mark the edge of something. Under these circumstances we should consider our actions in waking life a little more carefully.