These are set in the Project XRef and PFC Options tab
Example showing a link from a Recipe (diagram 13) above and a phase (diagram 35) below
Show Descend Link Arrows: This is on by default and makes an object that has 'Descendant links' to or from it show a vertical line to the left of symbol. If the symbol links to a descended object (see Defer functions) then the line has an arrow at the bottom end, if it is linked to from a parent diagram there is an arrow at the top end.
This is particularly useful when using models with Defer functions, for example to assign recipe parameters at a top level that are passed down to a lower level
Show Link Class Abbrev - causes the page number for a descendant link to be prefixed with the abbreviated class name of the page it is on. So if you link a parameter on a recipe procedure to a parameter on page ## and page ## is a phase the link will show as ph##. In addition if there are more than one links they are all indicated