I. If the signature series of a text is, for example:
A,A2,A3,A4,B,B2,B3,etc.
and the excerpt to be encoded begins on leaf P4r, then the signature gap before the excerpt will be written:
<gap extent="A-O4,P1r,P1v,P2r,P2v,P3r,P3v; pp..."/>
so that it is unambiguously clear that every gathering contains 4 leaves. Writing the gap as “A-P3v” is misleading, because it does not indicate how many leaves there are in each signature letter (or gathering).
II. Unsigned leaves are assigned the symbol khi (&khgr;) not only BETWEEN regular signatures, but also AFTER regular signatures. For example, if the collation of a text is:
A,A2,A3,B,...,Z,Z2,Z3,unsigned,unsigned,unsigned,unsigned
the signature series will be written in a gap as:
A-Z3,&khgr;4
III. If a text contains unnumbered pages BETWEEN or AFTER regular page numbers, e.g.:
pp. 1-65, 20 unnumbered pages, 66-100, 8 unnumbered pages
and suppose that the last page of the excerpt to be encoded is 58, then the page number gap AFTER the excerpt will be written:
<gap extent="...; pp. 59-65 + 20 unnumbered pages,66-100 + 8 unnumbered pages"/>
Also, in the same example, after the last page of the excerpt (58) is encoded (followed by the line gap, if there is one), there should be a <pb> for the first page of the gap, including the ideal page number but NOT including any milestones, as follows:
<pb n="59"/>
<gap extent="..."/>
IV. If a gap begins in the middle of a signature, the collation sequence in the extent= attribute should record each remaining page of that signature separately, to make clear exactly which pages are :
<gap extent="G2, G3, G4, H-L4..."/>