C.S.
Mom on the Go,
I am a third grade teacher with a masters in reading and diagnostic literacy, therefore I am quite familiar with scores being reported using a decimal point. Typically if a result is given without an additional key to help determine the results, they are using "grade equivalent" scoring. Thus meaning just as you said for K.4; kindergarten in the 4th month. With most standardized tests, this means scores are "normed" against other kindergarteners who have taken the test across the country. So they use that data to determine where within the grade level your child has performed.
In my opinion, I don't like using those kinds of tests to determine achievement. I think a test given for a short period of time on one day may not be a clear picture of your child's performance. A portfolio of progress using multiple types of assessments is the best way to really determine your child's reading achievement. Realistically, a test where a child colors in bubbles can have false scores just because the child didn't erase a smudge correctly. Another personal opinion: Those types of tests are NOT good at distinguishing the different parts of "reading." To say her "reading" level is K.4 doesn't really help anyone! You shouldn't be too concerend. I'd ask about her phonemic awareness skills, phonics blending and decoding skills, comprehension skills, and vocabulary development at the kindergarten level.
I hope this helps!