That's probably what it means. I'm in the US, and most states here have a "starting point" for division of property that the judge has the discretion to alter if the situation warrants it. As an example, in texas, the default division of marital property is 50/50. If, however, the wife worked full-time to put the husband through law school during the marriage, she would likely be entitled to some reimbursement of the money she contributed to his education. Also, in many states, if her earning capacity is substantially lower than his, they'll skew the initial division in her favor to where she'll get, say, 65%, to make up for that difference in future earnings. Finally, while a lot of states have "no fault" divorces, some still allow for additional changes to the division if the divorce was caused by one spouse's bad conduct, i.e. infidelity or abuse. So, if that lawyer was shacking up with his secretary, the spouse might get an extra 5-10% to penalize the husband for his douchebaggery.
My idol told me once that anything is negotiable. But, I'm not sure if this would be the best option for you. It'll probably be better to get a loan or seed money from venture capitalists than giving up a portion of the patent ownership to a law firm. It could have a damaging affect for your later goals. Do think it over.