command line interface – Does capital letter mean default option? [Y/n]

It’s pretty common for CLI tools make simple question and show the initial of the possible answers:

$ sudo apt-get install curl
Reading package lists... Done
Building dependency tree       
Reading state information... Done
After this operation, 29.8 TB of additional disk space will be used.
Do you want to continue? [Y/n] Y

I’d like to know if the capital letter is meant to be the default option.
If I press enter with no letter, does it mean “yes” in the above example?

I know it may vary from CLI to CLI, but is this a well stablished pattern?