README.md in unidom-common-0.3 vs README.md in unidom-common-0.4

@@ -39,5 +39,35 @@
 
 Project.coded_as('JIRA').valid_at(Time.now).alive(true)     # Same as Project.coded_as('JIRA').valid_at.alive
 team.projects.valid_during('2015-01-01'..'2015-12-31').dead
 Project.included_by([ id_1, id_2 ]).excluded_by id_3
 ```
+
+## ActiveRecord Migration Naming Convention
+### Domain Models (200YMMDDHHMMSS)
+* unidom-common:         200001DDHHMMSS
+* unidom-visitor:        200002DDHHMMSS
+* unidom-category:       200003DDHHMMSS
+* unidom-authorization:  200004DDHHMMSS
+* unidom-accounting:     200005DDHHMMSS
+* unidom-standard:       200006DDHHMMSS
+* unidom-party:          200101DDHHMMSS
+* unidom-certificate:    200102DDHHMMSS
+* unidom-contact:        200103DDHHMMSS
+* unidom-geo:            200104DDHHMMSS
+* unidom-property:       200105DDHHMMSS
+* unidom-article_number: 200201DDHHMMSS
+* unidom-product:        200202DDHHMMSS
+* unidom-price:          200203DDHHMMSS
+* unidom-commodity:      200204DDHHMMSS
+* unidom-shopping:       200205DDHHMMSS
+* unidom-order:          200206DDHHMMSS
+* unidom-promotion:      200207DDHHMMSS
+* unidom-payment:        200208DDHHMMSS
+
+### Country Extensions (200YMM9NNNMMSS)
+The YMM part should be identical to the relative part of the Domain Models.
+The NNN is the numeric code of [ISO 3166-1](https://en.wikipedia.org/wiki/ISO_3166-1 "codes for the names of countries, dependent territories, and special areas of geographical interest").
+The numeric code of China is 156.
+* unidom-certificate-china: 2001029156MMSS
+* unidom-contact-china:     2001039156MMSS
+* unidom-geo-china:         2001049156MMSS