Arrays should have value-based patch operations. Currently, only index-based actions are permitted:

• insert by index or last;
• replace by index;
• remove by index.

The current spec lacks value-based operations on arrays, such as:

• insert before/after certain existing values;
• replace existing values;
• remove by values.

For example, given:

{
    "items": [ "a", "c", "e", "z" ]
}

This patch should be valid:

[
    { "op": "add",     "path": "/items/-", "value": "b", "before": "c" },
    { "op": "replace", "path": "/items/-", "value": "d", "replace": "e" },
    { "op": "remove",  "path": "/items/-", "value": "z" }
]

And produce:

{
    "items": [ "a", "b", "c", "d" ]
}

The special - key, could be the indicator of an array at a specific path to keep compatibility with the current spec.