Is the only use of general-purpose register R0 as a stack pointer?

Basically, R0 is used as a stack pointer.

There are two types of stack pointer. The stack pointer select bit (U) of the processor status word (PSW) is used to select which stack pointer R0 is used as.

However, in a situation when neither interrupts nor subroutines are used, it is possible to use R0 as a general-purpose register that uses the same addressing mode as another general-purpose register.