This page uses the Infobox template shapenotetunebooktune. This article is the canonical example of how to use that template. The source page for that template mentions this article specifically.
This article has been marked for moving to the Wikisource project and removed as an independent article. It is not immediately apparent that this this is correct. The edit in which that mark was added is at http://en.wikipedia.org/w/index.php?title=Watchman_(hymn)&oldid=432864393
The criteria is "If the page can be edited into an encyclopedic article, rather than merely a copy of the source text."
However this article is not merely a copy of the source text. This article contains a hand-made transcription of the lyrics. These were originally in a source image file that has not been OCR'd. This article contains hand-edited metadata per the options in Template:Infobox shapenotetunebooktune . These fields require human judgement, such as a link to an editable version and an appraisal of the copyright status. The image of the source page is itself not merely a copy but required curation and management.
The goal of an article on a tunebook is to make the original tune page a more flexible thing which can be edited and improved per the wiki process and wikipedia community. One of these pages starts out resembling a copy of the source but over time may grow into something with a substantial independent value.