Immediate scalar replication mode example

[a7med7asan15]

Hi OpenHw Team, In Immediate scalar replication mode section. It is described here:

Immediate scalar replication mode (.sci), vector-scalar operation. Operand 1 is treated as vector, while operand 2 is treated as a scalar and comes from an immediate. The immediate is either sign- or zero-extended, depending on the operation. If not specified, the immediate is sign-extended. e.g. cv.add.sci.h x3,x2,0xDA performs: x3[31:16] = x2[31:16] + 0xFFDA x3[15: 0] = x2[15: 0] + 0xFFDA

The immediate is only 6 bits wide, Shouldn't the maximum value for the immediate to be 0x3F (0011 1111) ? Why the example mentioned 0xDA (1101 1010) ?

Also in the decoding tables, Sometimes the immediate is Imm6[5:0]s or Imm6[5:0], What is the difference between both? With and without the letter s

Thanks