 But UXP-based applications, like web browsers Pale Moon and Basilisk, keep supporting (NPAPI) plugins.Plug-ins appeared as early as the mid 1970s, when the EDT text editor running on the Unisys VS/9 operating system using the UNIVAC Series 90 mainframe computers provided the ability to run a program from the editor and to allow such a program to access the editor buffer, thus allowing an external program to access an edit session in memory.The plug-in program could make calls to the editor to have it perform text-editing services upon the buffer that the editor shared with the plug-in.