GPS Coordinate Conversions

Hi,
As you know there are three basic formats for reporting Lat/Long:
Decimal
Degree/Minutes
Degree/Minutes/Seconds

The latter two formats utilize "punctuation" to distinguish. For example the DM format would look like

N 27.09.070'
W 82.02.082'

And the DMS format"

N 27.10'.123"
W 82.11'.119"

the Problem is when publishers don't use any punctuation.
Then it can be unclear what format they are using and obviously the numbers become useless, or at least less helpful.

Here are a few examples I have come across

Example 1: N2717.178 - W8235.987
At first I thought this might be the old decimal system but I thought there should be more integers if that were true. Conversely, it is not possible to know if the last three digits are fraction of minutes or seconds.

Example 2: N27 09.070 W82 40.082
This seems to be the most common. Again, the last three digits could be either fraction of a minute or seconds. WO the "punctuation" how do I distinguish?

This is very problematic when I go to enter waypoints into my plotter (especially fishing spots or passes). Waypoints will be reported as XX.XX.XXX but I am not sure if they are using DM or DMS format. Then there is the XXXX.XXX format as in example 1. What on earth is that?

So, is there a convention I am not aware of? There are a plethora of tools online to convert between formats, but these tools are of limited utility if one does not know with which format he is working. Interestingly there seem to be a lot of tools to convert between decimal and DM or DMS formats and visa versa but very few to convert between DMS and DM and DM to DMS. This is interesting because these two formats seem to be the most common and therefore would be the most likely needed to be converted. To my knowledge and in my small little world nobody uses the decimal system despite its advantages (easy decimal arithmetic to calculate distances, etc).

Thanks!

John