Current State

In the admin-api api chapter ( https://apisix.apache.org/docs/apisix/admin-api/ ) all the examples for defining SSL, Upstream and Route use an {id}

In the Request methods it is indicated as {...}

In all examples this {id} is a numeric string

There is no explanation of the {id} syntax

Desired State

Add the syntax rules for {id}:

1. is it numeric
2. is it a string

If it is a string:

1. what is the max length
2. what characters are allowed (letter, numbers, special as - _ . # @ )