APPENDIX H 
mutations should be made wherever possible and the product of these 
-8 
should be less than 10 . Restriction-modification barriers should not 
be included in this test. 
II. Modifications in the definition of EK2 phage vectors 
The Working Group recommends specifically that: Lysogens of 
any EK2 vector carrying a cloned fragment formed in vitro should be 
considered as EKl systems. 
Appendix H--5 
