The group of elements that are part of a wellbore interval. The type of interval. The date when the interval was created. The date and time when the interval was created. The measured depth at the top of the interval. The measured depth at the base of the interval. The true vertical depth at the top of the interval. The true vertical depth at the base of the interval. A description of the perforations in this interval. Commonly specified for fraced intervals. A description of a single fracturing stage. A recording of a status with regard to the interval An event associated with the interval. A textual remark about the interval.