mrp.property is a class created by the procurement module, and it looks like this:

class mrp_property_group(osv.osv):
    """
    Group of mrp properties.
    """
    _name = 'mrp.property.group'
    _description = 'Property Group'
    _columns = {
        'name': fields.char('Property Group', size=64, required=True),
        'description': fields.text('Description'),
    }
mrp_property_group()

class mrp_property(osv.osv):
    """
    Properties of mrp.
    """
    _name = 'mrp.property'
    _description = 'Property'
    _columns = {
        'name': fields.char('Name', size=64, required=True),
        'composition': fields.selection([('min','min'),('max','max'),('plus','plus')], 'Properties composition', required=True, help="Not used in computations, for information purpose only."),
        'group_id': fields.many2one('mrp.property.group', 'Property Group', required=True),
        'description': fields.text('Description'),
    }
    _defaults = {
        'composition': lambda *a: 'min',
    }
mrp_property()

My question is, more or less, what is this, and why does it exist?

Clearly it is a means of associating "properties" to various objects, such as procurement.order and sale.order.line. However, I can't see how they are currently used, nor even how they are intended to be used.

1. You cannot associate mrp.property with product.product or product.template. From this, I gather that these are meant to exists "below" the product layer - that is, they are more like notes to the mrp workshop.

2. You can associate mrp.property with sale.order.line. This goes against what I expected, since if these are notes to the mrp group, why does the sales team know about them? And since they are not part of the product, the only place to begin applying them is by the sales people?

3. mrp.property is associated with procurement.order, but it is unclear what this is for.

4. mrp.property, if specified on a sale.order.line, is not propagated to the created procurement.order for the lines. In other words, even if these were used at the sales layer, they effectively will never leave it.

5. Similiarly, although mrp.property is associated with procurement.order, it doesn't go anywhere from here. It seems to be suggested that they could be used to pick a mrp.bom, since it is related there, but that is currently unused.

6. A mrp.production is entirely unrelated to mrp.property, and each mrp.production.line is similiarly unrelated.

So, my questions are:

1. Just what /is/ this?

2. What can it be used for right now?

3. What might one use it for? Can you offer examples?