Impacted versions:
11.0

I don't know if it is an issue, but I think is strange.

`product_qty` is in unit of `product` : https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L240
`reserved_availability` is in unit of `stock.move` : https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L295

`move.product_qty - move.reserved_availability` seems to have no sens, no ?

https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L915
https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L917
https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L924

thank for your answer

@jco-odoo 
@alnslang 


if self.env.context.get('default_picking_id'):
            return self.env['stock.picking'].browse(self.env.context['default_picking_id']).group_id.id
        return False
    name = fields.Char('Description', index=True, required=True)
    sequence = fields.Integer('Sequence', default=10)
    priority = fields.Selection(PROCUREMENT_PRIORITIES, 'Priority', default='1')
    create_date = fields.Datetime('Creation Date', index=True, readonly=True)
    date = fields.Datetime(
        'Date', default=fields.Datetime.now, index=True, required=True,
        states={'done': [('readonly', True)]},
        help="Move date: scheduled date until move is done, then date of actual move processing")
    company_id = fields.Many2one(
        'res.company', 'Company',
        default=lambda self: self.env['res.company']._company_default_get('stock.move'),
        index=True, required=True)
    date_expected = fields.Datetime(
        'Expected Date', default=fields.Datetime.now, index=True, required=True,
        states={'done': [('readonly', True)]},
        help="Scheduled date for the processing of this move")
    product_id = fields.Many2one(
        'product.product', 'Product',
        domain=[('type', 'in', ['product', 'consu'])], index=True, required=True,
        states={'done': [('readonly', True)]})
    ordered_qty = fields.Float('Ordered Quantity', digits=dp.get_precision('Product Unit of Measure'))