Good question. It's the pin-to-pin logic delay of the device.
XC95xx come in several sizes (macrocells) each size is tested and given a speed rating, -10, -7, -15 etc. This figure is the tpd in nanoseconds: you can expect to pay more for the faster devices, but with the benefit that you can run them at a higher frequency. The way to distinguish them is in the part number
One vital thing to note is that this is NOT the same as FPGA markings, FPGA have a speed grade, which does not directly correspond to any tpd, and higher numbers are FASTER, the opposite of CPLD markings (from my experience)
Having looked in the datasheet (belatently) there is another question, in the top of the datasheet the pin to pin delay is quoted as 5ns, then down below we see also 6ns 7ns 10ns 15ns. So do they mean to say that 5ns is the fastest one, but slower one are also available?
Another question, I have here a xc9536 which has the following marking
xc9536 tm pc44amm0521 f3002413a
What speed would it be? I can't find the ordering number on the part, or should have I made a note of it when I bought it (so how would I to know if my supplier did not send me a different spec?)
Changing the "10C" to "7C" in the illustration to match your part would make the following text applicable:
Line 4 Device speed grade (7) and temperature range (C). If a grade is not marked on the package, the product is considered commercial grade.
In addition to the mark shown above, Line 4 can contain a few other variations as described below:
7C xxxx The "xxxx" indicates the SCD for the device. An SCD is a special ordering code that is not always marked in the device top mark.
7CES The "ES" indicates an Engineering Sample (as opposed to a production device).
7CESn The "n" is a numeral (1, 2, 3, etc.) The "ES" indicates an Engineering Sample, the "n" indicates an ES revision code. For example, ES1, ES2, ES3, etc. Please see Errata for appropriate information. To obtain Errata, you must register for MySupport, see (Xilinx Answer 21491).
7CESnL or 7CESnR This part marking is used only for Virtex-4 FX engineering sample devices. The "L" indicates that only left (column 0) MGTs are available and the "R" indicates that only the right (column 1) MGTs are available when looking at the device from the "bottom-up."
I asked if you looked at Solution2 for that Answer record. By the "I couldn't find it no matter *how* hard I looked tone in your response, I figured you had trouble connecting simple images and phrases with the information being conveyed. I thought that if I cut & pasted the quotes for the 10C value USED IN THE ILLUSTRATION IN THE ANSWER RECORD that you would obviously get confused. So I requoted the text to show the "7C" you have on your part. I only mentioned the "10C" to avoid having you say that the text I quoted wasn't in the Answer record.
Additionally, the xc9536 data sheet on page 7
shows the device marking explicitly calling out the "Speed" number.
You appear to not bother 1) read the data sheet, 2) read the answer record that was provided to you as a link, and/or 3) prefer to have everything handed to you in such an outrageously clear fashion that a third generation tropical island castaway would understand what the marking on the device meant.
We helped. You returned, helpless. You complained.
Just FYI: it qualifies him as someone whose first language wasn't English, making him particularly sensitive to the issues faced by those who try to communicate on this board with an excellent written word but who miss the more subtle meanings in these newsgroup communications and in technical documentation.
This group is filled with much expertise and most participants are MORE than willing to help in anyway they can. I've seen them give students answers to their homework, and give engineers help with debugging and overcoming design hurdles. The only thing any of the aforementioned SME's expect is that those posting questions would be polite, truthful, and professional. There's a wealth of knowledge on this board that is made available to anyone earnestly seeking answers.
There's an old proverb which says that "a wise man will hear, and will increase learning, and a man of understanding shall attain unto wise counsels". You've done properly by contacting this group (wise counsel), but unless you are willing to HEAR and listen to that wisdom you're nothing more than a fool.
Here's a piece of advice: stay humble, don't react when filled with emotion, and be willing to take criticism.