12.6.3 Simple-page-sequence Flow Object Class
The facilities in this clause require the simple-page feature.
A simple-page-sequence flow object class is formatted to produce a sequence of page areas.  A simple-page-sequence flow object has a single principal port that accepts any displayed flow object.

NOTE 57

The simple-page-sequence flow object is intended for systems that wish to provide a very simple page layout facility.  More complex page layouts can be obtained with the page-sequence and column-set-sequence flow object classes.
A simple-page-sequence flow object shall not be allowed within the content of any other flow object class.
A simple-page-sequence may have a single-line header and footer containing text that is constant except for a page number.

NOTE 58

A document can contain multiple simple-page-sequences.  For example, each chapter of a document could be a separate simple-page-sequence; this would allow the chapter title within a header or footer line.
The page shall be filled from top to bottom.  The display-size for the contents of the simple-page-sequence shall be the value of the page-width: less the value of the left-margin: and right-margin: characteristics.
A simple-page-sequence flow object has the following characteristics:

•  page-width: is a length specifying the total width of the page. The initial value is system-dependent.

•  page-height: is a length specifying the total height of the page. The initial value is system-dependent.

•  left-margin: is a length specifying the left margin. The initial value is 0pt.

•  right-margin: is a length specifying the right margin. The initial value is 0pt.

•  top-margin: is a length specifying the distance from the top of the page to the top of the area container used for the content of the simple-page-sequence. The initial value is 0pt.

NOTE 59

The header line is within the top margin.

•  bottom-margin: is a length specifying the distance from the bottom of the page to the bottom of the area container used for the content of the simple-page-sequence. The initial value is 0pt.

NOTE 60

The footer line is within the bottom margin.

•  header-margin: is a length specifying the distance from the top of the page to the placement path for the header line. The initial value is 0pt.

•  footer-margin: is a length specifying the distance from the bottom of the page to the placement path for the footer line. The initial value is 0pt.

•  left-header: is an unlabeled sosofo containing only inline flow objects that is aligned with the left margin of the page in the header line. This characteristic is not inherited. The default value is an empty sosofo.

•  center-header: is an unlabeled sosofo containing only inline flow objects that is centered between the left and right margins of the page in the header line.  This characteristic is not inherited. The default value is an empty sosofo.

•  right-header: is an unlabeled sosofo containing only inline flow objects that is aligned with the right margin of the page in the header line.  This characteristic is not inherited.  The default value is an empty sosofo.

•  left-footer: is an unlabeled sosofo containing only inline flow objects that is aligned with the left margin of the page in the footer line. This characteristic is not inherited.  The default value is an empty sosofo.

•  center-footer: is an unlabeled sosofo containing only inline flow objects that is centered between the left and right margins of the page in the footer line.  This characteristic is not inherited. The default value is an empty sosofo.

•  right-footer: is an unlabeled sosofo containing only inline flow objects that is aligned with the right margin of the page in footer line.  This characteristic is not inherited.  The default value is an empty sosofo.

•  writing-mode: is one of the symbols left-to-right or right-to-left.  This determines the writing-mode of the header and footer lines.  The initial value is left-to-right.
(page-number-sosofo)
Returns an indirect-sosofo whose content is a sequence of character flow objects representing the page number of the page on which the first area resulting from the indirect flow object specified by the indirect-sosofo occurs.
(current-node-page-number-sosofo)
Returns an indirect-sosofo whose content is a sequence of character flow objects representing the page number of the primary flow object of the current node.

NOTE 61

This is intended to handle cross references in conjunction with process-element-with-id.