What syntax should I use for the labels present in the query string of a hit?

We divide the variables of the query string of the hit with the sign &. After each sign &, we count a new parameter. The & sign, therefore, takes precedence over the brackets surrounding a label. 

The following rules should apply to the wording:

• No accented characters

• No space (spaces should be replaced by underscores, i.e "_")

• No characters other than letters and numbers (do not use commas, "+", quotations marks or apostrophes).

Authorized characters are:

• Letters (abcdefghijklmnopqrstuvwxyz (upper or lower case))

• The numbers 1234567890

• Periods/dots  .

• Slashes /

• Dash –

• Underscores _

• Tildes ~

Please note that special characters can be used provided that they are encoded. For instance, instead of "cars&motorbikes", please use "cars%26motorbikes".