A servicemark is a trademark. It just means a trademark for a service rather than for a good. A housemark is a trademark like "Nanotech Entertainment" which is a mark that is used for many services and/or good that are produced and/or marketed by the same entity (or 'house').
Here's an example:
"Merck" and Merck & Co. a housemark of Merck & Co. The "Merck Manual" is a trademark for the good of a medical manual produced and sold by Merck. "Zocor" is a trademark of Merck for that good sold in commerce and is also called a brandname. The generic name for that drug is "simvastatin" and cannot be trademarked by anyone as it is an approved USAN/INN generic name. If Merck also provided a service (let's say they did drug dispensing as a mail order pharmacy to consumers for a fee and called it "MyOnlinePharmacy"), that would be a servicemark.
On a bottle of Zocor, the name "Zocor" is a trademarked brandname, the name "Merck & Co." on the bottle is a trademarked brandname, and if they sold all kinds of drugs in an online pharmacy called "MyOnlinePharmacy" that would be a trademarked servicemark.
All three (housemarks, brandnames, and servicemarks) are trademarks and they are called trademarks and registered. A registration in th PTO does NOT create a trademark, is only is a presumptive claim to own it that provides a rebuttable presumption to the registrant if they sue someone in a US court for trademark misappropriation, trademark misuse, trademark dilution, to oppose the registration of the mark for another company or person for use in a different field of use, etc.
In any case, "the future of television" for the field of distributing media content was registered by NTEK butt it's now DEAD, having been abandoned a year ago.
Hope that helps.
