Editorial style also affects partial barre indications. A vertical strike-through of the letter "C" commonly indicates a partial barre—the number of strings to barre depends on context and performer choice. Other editorial styles use superscript fractions (e.g., 4/6, 1/2) indicates the number of strings to barre in addition to the letters B or C. In some notation styles (particularly classical staff notation), the letters "B" or "C" are omitted altogether, with the number of courses to barre (from the highest-tuned downwards) written as an index (superscript). For example: on a guitar, VII4 indicates a barre on the 7th fret over the highest four strings (D, G, B, and E). There is no rule for whether to write "full" barre chords with indices (e.g., "6" for a standard guitar) or without. It is a matter of the editors personal taste. It is customary to place the barre sign above the staff, with a spanning line to mark duration.