This box is used as a module in the {{Chembox}}. This template does not have any parameters, it only shows output if page "{{pagename}} (data page)" exists. See the example below for Ammonia, where Ammonia (data page) exists.

Chembox Supplement/doc
Supplementary data page
[[]]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

By default, the name for the data page is [[<pagename> (data page)]]. So for ammonia, that is Ammonia (data page).

In some situations it may be needed to overwrite that default name:

|data page pagename=Some other page.

This will supporess showing the data page link:

|data page pagename=none.