Where Can You Find a Complete List of the Reserved Words for Declarative Pipeline Syntax?

Problem scenario
You want to create a Jenksinfile for a pipeline. Where can you find a complete list of the reserved words for Declarative pipeline syntax?

Answer
This external page has something close. It does not go into into how "sh" works. Using "sh" you can run Linux commands. There are "bat" and "powershell" options too. Here is an example (taken from Jenkins' website) :

pipeline {
     agent any
     stages {
         stage('Build') {
             steps {
                 sh 'echo "Hello World"'
                 sh '''
                     echo "Multiline shell steps works too"
                     ls -lah
                 '''
             }
         }
     }
 }