Starting filling out how selector matching works

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extra : rebase_source : 8b7a8044c0f2678731c5351000a5bcd65cd9d3d3
Rename speed to playback-rate

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extra : rebase_source : 13534680fd928088fb7bfefc1f2690d9ac0a7d87
Add direction attribute to change list

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extra : rebase_source : 2e2ec46e19d415b373a4005a8d9e4213daa0ee0e
Replace references to playWith with beginElement(At)

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extra : rebase_source : ea82fe9674f623a92cf21190d024a417b71e24e4
Add cross-references from changes list to sections now added