# Changes in the H5MD file format¶

## Changes in H5MD 1.1¶

1. The development process for H5MD is based on proposals

Proposals are motivated and present a change to the file format in detail. A change should be accompanied by sample code to test the viability of an idea. This change is formalised in proposal 1.

2. Proposal 100: Storage of time information

Several changes are made: The time dataset can be left out if it is not needed. The step and time datasets can be scalar, in which case the data is mandatorily sampled at equal time intervals.

3. Proposal 101: Particles and tuples lists

A storage layout is defined for lists of particles and lists of tuples of particles.

4. Proposal 102: Storage of charges

Charges can be stored in a particles group along other per-particle data.

5. proposal 103: Connectivity group

The storage layout defined in proposal 101 is used to unify the storage of connectivity information, i.e. lists of pairs (or bonds), etc.