SQL select records in special order

The plain SQL statement “SELECT * FROM mrcdct16” returns:

RETRN   SEQNO  RECRD        FIELD  
 2,710      6   ORDDETF     ORDNUM 
   100      5   INCIDENTR   EMP#   
   102      7   ORDDETHISR  ORDNUM 
   106      7   ORDERHEADR  CUSNO  
   101      5   INCIDENTR   EMP#   
     1      4   INCIDENTR   EMP#   
 2,740      7   ORDDETHISR  ORDNUM 
   103      5   INCIDENTR   EMP#   
   105      5   INCIDENTR   EMP#   
     6      7   ORDERHEADR  CUSNO  
   107      7   ORDERHEADR  CUSNO   

We want to select records with the first letter in FIELD to be E, C, O. We can use SQL

SELECT * FROM mrcdct16 order by position (substring(field, 1, 1) in 'ECO')

100      5   INCIDENTR   EMP#           2
101      5   INCIDENTR   EMP#           2
  1      4   INCIDENTR   EMP#           2
103      5   INCIDENTR   EMP#           2
105      5   INCIDENTR   EMP#           2
106      7   ORDERHEADR  CUSNO          2
  6      7   ORDERHEADR  CUSNO          2
107      7   ORDERHEADR  CUSNO          2
710      6   ORDDETF     ORDNUM         2
750      6   ORDDETF     ORDNUM         2

Or select them with 2 letters in FIELD as EM,OR,CU

SELECT * FROM mrcdct16 order by position (substring(field, 1, 2) in 'EMORCU')

Then we get:

  100      5   INCIDENTR   EMP#           2 
  101      5   INCIDENTR   EMP#           2 
    1      4   INCIDENTR   EMP#           2 
  103      5   INCIDENTR   EMP#           2 
  105      5   INCIDENTR   EMP#           2 
2,710      6   ORDDETF     ORDNUM         2 
2,750      6   ORDDETF     ORDNUM         2 
  106      7   ORDERHEADR  CUSNO          2
    6      7   ORDERHEADR  CUSNO          2
  107      7   ORDERHEADR  CUSNO          2