Polish Family Info Death Index
This database of deaths is from Polish parishes primarily in the US but also some in Poland. See the list of indexed parishes. Even though the results page will show many columns, most parishes only recorded the date, the name of the deceased, and their age. In that sense, this is the least useful of the databases. However, some parishes were more generous with the information they included. That was the justification for adding the extra columns. The Notes column may show a cause of death, but it may also show the name of a surviving relative. Do not assume the relative was the cause of someone's death!
Like most death records, ages tend to be the least reliable pieces of information. Ages are usually offered by children who didn't really know how old their parent was and during a time of grief when they're not always thinking straight. Another problem with ages is how they were recorded. In most cases, it's clear, but there are situations when the age is caught in the binding of the death register, left off completely, or there is confusion about the units of time. For example, "5 h" might be interpreted as 5 hours or 5 weeks (in Latin). So an age could be off quite a bit and points out the importance of checking it out yourself before putting too much stock in what this index says. In some parishes, a missing age often (but not always) meant the person was either stillborn or only a few days old.
On the results page, the Spouse column may show w or s where w indicates widow/er status and s indicates spouse-- the person was married even if the spouse is not named. Age is given using y for years, d for days, w for weeks, m for months, or h for hours. When no date abbreviation is used, the age is in years. Generally, a woman is indexed by her maiden surname if known or inferred. But, she might also be indexed under her married name if there was no evidence to suggest that she was married. I assumed the woman was married if her surname was different than her father's surname. One could argue that the names are different because she had a stepfather. If that was the case, I would have expected to find the same phenomenon happening for deceased males as well (and I didn't). The search engine searches BOTH the Surname and Spouse Surname field for matches to overcome the married/maiden-name problem.
Let's talk about the search form. The "Search option" rationale is discussed in the article, Searching Databases Efficiently, and also summarized at the bottom of this search form. This database also has a "Search by" selector. Most of the time you are looking for the death of a particular person (the Decedent). Sometimes it might be helpful to answer the question "Which children (of a given father) are included in the index?" In this case you would use the Father option. Don't expect lots of matches because the father's name was not commonly given in the record. The mother's name was even more rarely included, so searching by the mother was not implemented. The Normal, Soundex, and Look-alike option are explained here. Normal is the default option and most generally useful.
exact match: enter the name exactly the way you want it found (e.g., Adam will find ONLY Adam).
match first: enter the first part of name to be matched (e.g., Adam will find Adam, Adamik, Adamowski).
wildcard search: enter any part of the name (e.g., Adam will find Adam, Adamik, Adamowski, and Hadam).
Provided you are using "match first" or "wildcard search", you may use the % character to represent any number of letters and the _ (underline) character to represent one specific letter. Additional explanation here.