OFFICIALS - RECRUITMENT - ASSIGNMENT OF GRADE AND CLASSIFICATION IN STEP - ' ' DECISION ' ' OF AN INSTITUTION CONCERNING APPLICABLE CRITERIA - LEGAL NATURE - INTERNAL DIRECTIVE - EFFECTS A ' ' DECISION ' ' OF AN INSTITUTION ON THE CRITERIA APPLICABLE TO GRADE AND STEP CLASSIFICATION UPON RECRUITMENT OF OFFICIALS , COMMUNICATED TO ALL THE INSTITUTION ' S STAFF BY MEANS OF A NOTICE COMPRISING THE ABOVE-MENTIONED DECISION ( ANNEX I ), A STATEMENT OF THE PRACTICE RELATING TO ITS APPLICATION ( ANNEX II ) AND A LIST DESCRIBING THE MEMBERSHIP OF THE GRADING COMMITTEE ( ANNEX III ), CONSTITUTES AN INTERNAL DIRECTIVE WHICH SHOULD BE REGARDED AS A RULE OF CONDUCT INDICATING THE PRACTICE TO BE FOLLOWED , WHICH THE ADMINISTRATION IMPOSES ON ITSELF AND FROM WHICH IT MAY NOT DEPART WITHOUT SPECIFYING THE REASONS WHICH HAVE LED IT TO DO SO , SINCE OTHERWISE THE PRINCIPLE OF EQUALITY OF TREATMENT WOULD BE INFRINGED . THE SAME CONSIDERATIONS MUST APPLY WITH REGARD TO THE LEGAL NATURE OF ANNEX II TO THE NOTICE , ENTITLED ' ' PRACTICAL APPLICATION - GENERAL SURVEY ' ' , WHICH BRIEFLY DESCRIBES THE ' ' ESTABLISHED PRACTICE ' ' OF THE ADMINISTRATION IN APPLYING THE PROVISIONS LAID DOWN IN THE ' ' DECISION ' ' IN QUESTION , BY SETTING FORTH MORE SPECIFIC RULES WHICH THE ADMINISTRATION CONSIDERS ITSELF BOUND TO OBSERVE . IN CASE 25/83