@jaybee actually it's more on consistency. kung hindi naman pwede ok lang. sigurista lang kasi ako =) usually kasi sa mga COE, job title/position and length of stay lang nilalagay. sa ibang company, itatanong ka kasi ng HR(or kung sino man incharge) kung ano pa gusto mo ilagay nila aside from those two. It may be salary, positions gained throughout your stay, duties/responsibilities, etc.
Mas ok lang kung detailed yung COE kasi it's coming from the employer mismo. not like in CV na from the individual lang (pwede kasi imbento lang).
Another good evidence of employment siguro is reference letter from your previous superior. pero dapat in company letterhead pa din. tapos dun nakalagay yung duties/responsibilities mo.
Basta always check for the consistency of your documents. yung mga simpleng error lang sa CV like duration of employment or minsan sa COE mismo mali nakalagay kaya double check it before you lodge all documents.