IFR stands for International Financial Reporting.
During IFR flight, ATC will dictate cruising altitude.
Issued For Review
Any pilot (PIC) wishing to operate under IFR at Sion shall be trained and qualified for the local IFR Procedures with an aircraft able to operate on the IGS Steep Approach (initial 6 degree glide path
VFR or Visual Flight Rules means you generally have good visibility and are in a certain range of altitudes. You basically fly using what you see (and of course navaids and charts). IFR or Instrument Flight Rules are used at certain altitudes, with certain types of aircraft and under certain kinds of visibility. Under IFR, you fly by using navaids, charts and instruments. Oftentimes you'll have zero visibility but IFR lets you fly in these assuming you're IFR certified.
Initial Fire Response
The VFR hold line is the line on the taxi way which vehicles are not allowed to cross without permission from ATC during VFR weather conditions. The IFR hold line serves the same purposes but during IFR weather. In most places there will simply be a "hold line" which serves as the hold line during both VFR and IFR conditions.... but in situations where an aircraft waiting at the hold line may interfere with ground-based radio signals (such as an ILS approach signal) an IFR hold line may be positioned farther back from the runway to reduce this risk.
The layout is basically the same. This is because pilots from all over the world need to interact with Departure and Arrivals chart instruction and routes plus airport requirements.
Use IFR plan or your visual flight rules
IFR departure routes
Before Encountering IFR Conditions Bureau of Industrial and Financial Reconstruction (India)
Regarding the mail delivery system, IFR hasn't any meaning. This isn't a French postal code or abbreviation. That could probably be part of the name of the business you are writing to, or an internal abbreviation privvy to the sendee.