# API Reference

## Periods

class ActivePeriodMixin

  This mixin makes it easy to create a `Model` which is active between a start and end date. The date range, Periods <model-account.period>, or Fiscal Years <model-account.fiscalyear> that are set in the context are used to determine if a particular record should be considered active, or not.

class PeriodMixin

  This mixin provides a start and end date to classes that inherit it. It also limits any parent or child fields of the class to the same Company <company:model-company.company> and to dates in the same period.

## Taxation

class TaxableMixin

  This is a mixin that helps create classes that need to calculate Taxes <model-account.tax>, tax lines, and tax and base amounts from a list of taxable lines.

# Development Reference

The Account Module includes minimal charts of accounts for many languages. The XML files that contain the localised charts of account are all generated from the same source XML file. The `localize.xsl` XSLT file defines how the source XML file is transformed into a localised chart of accounts.

To output a localised chart of accounts for language `<lang>` run:

    xsltproc --stringparam lang <lang> localize.xsl minimal_chart.xml