This was originally reported via Typo report form. Transforming into ZBX:
As per documentation "Parameters specify the variables to be passed to the script as the attribute and value pairs.
Built-in macros {HOST.CONN}, {HOST.DNS}, {HOST.HOST}, {HOST.IP}, {HOST.NAME}, {ITEM.ID}, {ITEM.KEY}, {ITEM.KEY.ORIG} and user macros are supported."
User's comment: I give a try in the parameters, but it did not work. Just define a parameter and return it in the code:
parameter cong 48
Script return cong
this give an error saying cong is not defined. Please include an example, may be as simple as this one

Documentation page
Source file