From Xiao et al. BMC Anesthesiol. 2013; 13: 33. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4016475/):
The pre-publication history for this paper can be accessed here:
http://www.biomedcentral.com/1471-2253/13/33/prepub
A textual entity that expresses the pre-publication history (submission dates, reviewer comments, etc) for a document, often including a hyperlink to a web page detailing the information.