Entities disappear in the void

Works as intended. Any entity that enters the void is automatically deleted since the void technically does not exist in the world files. (Negative Y-values do not exist)

You are wrong. Entity Y-position is stored as a float value and therefore negative position is technically well possible. This may be intended, but not reasonable.

Can this be reopened? This is not intended; entities are not deleted in the void; some merely stop rendering. They still exist and are still saved to disk. It even applies to players entering the void (you can see this in third-person mode), and those clearly are not deleted.

Steps to Reproduce:

1. Use a Spawn Bat egg on the bottom surface of the bedrock

2. Observe that no bat is visible, but it makes its usual squeaking and flapping sounds

3. If the bat has particle effects, the particles will be visible, but the bat will remain invisible

4. If the bat flies above y 0, it will become visible

This is a rendering bug, not a consequence of "negative y-values do not exist". Negative y values do exist; entities with negative y values are explicitly stored in the lowest chunk section in save data. Also, until the 1.8 snapshots, this behavior of vanishing entities did not exist.

This bug also applies to y-values above 255.
Steps to Reproduce:

1. Shoot an arrow upwards while you are near y 255

2. Observe that the arrow vanishes when it goes higher than y 255

3. Observe that it re-appears once it falls back to below y 255

That seriously can't be intended, and does not make any sense.

Also, confirmed for 14w08a. Can a moderator please re-open and update the title/description to acknowledge that this also applies to y values above 255, and applies to players (including oneself in third-person mode)?

Reopened.
Same issue as MC-45067 (Player does not render below -1.8)

Confirmed for 14w08a and 14w10c

Confirmed for 14w18a

also in 14w27b

fixed in 14w28b

Cannot set 14w28a as fixed version anymore, setting 14w29a.