Syntax - . - Floating-Point Number Literal
Characters: .
The beginners' page has a more thorough explanation of Jelly syntax and tokenization.
Functionality
Floating point decimal. .y is equivalent to 0.y and x. is equivalent to x.5.
Details
The binding order for number literals is ., -, ȷ, and finally ı, so the maximum number of components a number literal can have is -a.bȷ-c.dı-e.fȷ-g.h.