itsp/MaxSubscreenNames is a SAP Parameter attribute which is used to control SAP Gui for HTML, maximum subscreen names information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Maximum number of subscreens. The value specifies the maximum number of
subscreen slots on one screen.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.