How can I access Texcoords x and y?

So, If I write this it’s all right

IN.uv_Splat0

but if I write

float2(IN.uv_Splat0.x, IN.uv_Splat0.y)

it doesn’t work properly

Is there a way to access and modify uv’s x and y in a shader?

float2((frac(IN.uv_Splat0.x/7)*-0.5), (frac(IN.uv_Splat0.y/7)*0.5))