Bedrock Edition:Oak Log
Oak logs were discontinued as an item starting in Pocket Edition v0.2.0 alpha and as a part of natural generation starting in v0.2.1 alpha. They were recontinued in v0.4.0.
When survival mode was introduced in v0.2.0, oak logs became unobtainable without external editing or downgrading. Oak logs did still generate in this version and dropped themselves when mined, but dropped oak log items could not be picked up due to them not having an associated slot in the inventory. In v0.2.1, oak trees started generating with spruce logs instead of oak logs, though this did not change any previously generated oak trees. In v0.2.1 alpha2 and v0.2.2, any oak logs in loaded chunks were automatically replaced with spruce logs. From v0.3.0 to v0.3.3, oak logs in the inventory were converted to spruce logs once the player exited and re-entered the world. Starting in v0.4.0, oak trees once again generated with oak logs and the player could obtain them normally.
Obtaining
Pre-v0.2.0
Oak logs were available in the inventory and generated as the trunks of oak trees.