1. document api: getelementsbytagname

2. document api: getelementsbytagnamens

3. element api: getelementsbytagname

4. element api: getelementsbytagnamens

5. element api: getelementsbytagnamens: `getelementsbytagnamens(namespaceuri, "*")`

6. element api: getelementsbytagname: `getelementsbytagname("*")`