这是IEA的说法。原文如下:
If in your CV/resumé you claim engineering work experience
of 12 months or more, then you must provide certified copies
of original employer reference letter(s), and certified
translations into English where necessary.
If a career episode is based upon engineering work, then you
must provide an employer reference letter.
所以个人理解:如果那段经历没到12月,而且也和三篇CDR无关,则可以不用提交那段时间的推荐信。