British Library:

Portable almanacs were most probably made to be used by physicians and those with an interest in astronomy, astrology and prognostication. They were small, consisting usually of 6 to 8 parchment leaves folded in half and then into 4 or 6 oblong sections, sewn together at one edge with a tab that could be fastened to the girdle with a piece of cord. On the outside of each section were often titles for easy reference so that the correct page could be selected. – See more at: http://britishlibrary.typepad.co.uk/digitisedmanuscripts/2015/12/all-manacs-on-line.html#sthash.7NFUandT.dpuf