再問高手有關EB1B的問題。萬謝！

打算辦EB1B, 但是咱們的雇主說他們從來沒在任何人的employment letter 上放上permanent 這個詞, but they can put a description like the following in my employment letter:
The research position is a position for an indefinite or unlimited duration, and in which the employee will ordinarily have an expectation of continued employment unless there is good cause for termination.
這樣可行嗎?