In practice, however, rules can usually be formulated to reduce the need for so much tagging. A poem always has a single title element which precedes the first stanza and contains no other elements. Apart from the title, a poem consists only of stanzas. Stanzas consist only of lines and every line is contained by a stanza. Nothing can follow a stanza except another stanza or the end of a poem.
Nothing can follow a line except another line or the start of a new stanza.
From these rules, it may be inferred that we do not need to mark the ends of stanzas or lines explicitly. O Rose thou art sick. Does thy life destroy. Before considering these rules further, you may wish to consider how text marked up in the form above could be processed by a computer for very many different purposes. Different parts of each poem could be typeset in different ways.