1. A method implemented on a computer comprising a processor, and for producing a sentiment marking for a multi-term text unit, the method comprising: receiving a text unit comprising multiple terms, each term comprising a word or a phrase in a language; identifying, in the text unit, a first term and a second term; identifying a first connotation value associated with the first term, and a second connotation value associated with the second term, wherein the first connotation value and the second connotation value is either a positive value or a negative value each representing an opinion or sentiment type or value, wherein neither the first term nor the second term includes the grammatical negator or the negation word of the language, and when the language is the English language, neither the first term nor the second term includes a syntactically or grammatically defined negator or negation word comprising the word “not” or “no”; identifying a grammatical attribute associated with the first term or the second term, wherein the grammatical attribute includes at least the grammatical roles of a subject, an object, a head, a modifier, and parts of speech of a noun, a verb, a preposition, an adjective, and adverb; and associating the text unit as a whole with a derived connotation value based on the first connotation value and the second connotation value, and the grammatical attribute, wherein the derived connotation value is different from either the first connotation value or the second connotation value; marking the text unit with the derived connotation value, or outputting the text unit as a text unit associated with the derived connotation value.