PMM said:
If an employer has an approved LMO for more than 1 employee, there are no names on the LMO. It is valid for obtaining a TWP as when the VO checks the system, the person's name does show up.
Agreed. But what you're describing is a (fully approved) LMO which merely has no names printed on the confirmation letter for privacy reasons, even though the names are known to HRSDC.
The OP is talking about (pre-approved) unnamed LMOs which are issued upon an employer's request before a foreign worker has been identified for the position. The reason HRSDC/SC issues such opinions is to benefit employers, many of whom prefer to have a pre-approved LMO in hand before they start recruiting overseas (or just to keep their options open). Unnamed LMOs cannot be used to obtain work permits because they are not full authorizations.
A recent poster (pultyn) alluded to this - he tried to flagpole with an unnamed LMO and was told to return once he had a proper one in hand. See:
http://www.canadavisa.com/canada-immigration-discussion-board/flag-pole-lmo-job-offer-and-t134844.0.html;msg2089453#msg2089453
If you refer back to the original post, the writer said: "I got an OPEN UNNAMED LMO from my employer, and he said that my name was already sent to Service Canada. Do i need to wait for the confirmation before I proceed to application of Visa? please help. because I only have 1 month then my LMO will be expired."
So (1) the writer himself says it's an open unnamed LMO, (2) he notes that his name was sent to SC (which implies it was sent AFTER the LMO was approved, hence making it an unnamed LMO, (3) he asks if he can apply for the WP before getting the confirmation as the LMO will expire in one month. Since he doesn't have a confirmed LMO, what he does have is an unnamed one. The fact that he received the LMO with one month left to expiry also indicates that it was unnamed and needed to have a name supplied to HRSDC/SC before being valid for use.
For what it's worth, HRSDC itself uses the terms LMO and unnamed LMO to distinguish between the two types of opinions.