how some signs are used in bibliography / templates ?

There are som signs in the template of bibliography just like small diamond and vertical seperator. One of them is seperator I think but I do not know the other one.  How should we use these signs while changing  or rearranging the template?

The tiny diamonds are called “link adjacent” and are used to connect the spaces and punctuation to a field.  When the field is absent, those spaces are excluded from the output.  They are used in conjuction with the separation “lines” to isolate those attached punctuation and link adjacent spaces.  I have never quite figured out when they are important and when they are redundant as long as they are between separation characters.