Coding question: {memberID}, {nickname}, et al

Can someone explain curly braces around variable names in Boonex Dolphin code? Namely:

• what is the complete list of these variables which can be referenced in places like Navigation Menu builder URLs (Admin > Builders > Navigation Menu)?
• where are these variables accessible, i.e., their scope?

Thanks in advance

Also, how can the values of these variables be determined?

The following variables aren't empty when user is logged in:

memberID
memberUsername
memberNick
memberLink

If profile page is current, then the following variables are also available:

profileID
profileUsername
profileNick
profileLink

You can use them in Link and Onclick fields.