Issue about instruction register length

I can find below words,

"The instruction register length is determined automatically by the Quartus II JTAG server."

But, i really want to know what's the exactly value or range. For i worry about that my instructions' number of visual jtag would beyond its range.

There are many visual jtag instrucions when i design VJ interface to debug my project, so this is a serious issue for me.