There is no fixed format But I used this one.
What they will be looking for is your salary, your job description and the time you have been working with the present company.
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June 25, 2003
To
The American Consulate General,
Vancouver, B.C.
Sub: Multiple Entry Visa for XXXXX
Dear Sir or Madam:
Mr. XXXXX is presently employed by YYYY since 01/01/1900 as a Systems Analyst ( Approved petition LIN #ZZZZZ). Mr. XXXXX current annual salary is $00,000.
His duties in this position include....Put your job description..
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If you have any questions or require any additional information, please free to call me.
Thanking you,
Sincerely,
Manager
BBBBBB
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Hope this Helps
Good luck!