Balanced salt solutions - (Apr/03/2005 )

What does it mean with balanced salt solutions and which ones are they?

Examples are:

Dulbecco's Phosphate-Buffered Saline (DPBS)

Hanks' Balanced Salt Solution (HBSS)

Phosphate-Buffered Saline (PBS)

My question is, what is the principal difference from the point of view of application, among Dulbecco-PBS and PBS itself. If the guys in the publication said that they washed Vero cells by PBS, it signify strictly PBS, or maybe DPBS???