You are welcome. I use eBay/stamps as a reference book, sometimes it surprises you what information is out there on it. I will cut and paste the info below for Rod, and others, to save.
(info below from an eBay
Note: All prices based on "Die Soldatenmarken der Schweiz" 1990 Katalog, published by Heinrich Sulser (the only recognized catalogue of Swiss Soldier Stamps)
Military "Soldier" Stamps
During each World War, the Swiss military mobilized to ensure that Switzerland would not become one of the participants. Since Swiss military service is compulsory for all men between the ages of 18 and 48, this inevitably created financial hardship for many of those called up for active duty. During each war, individual military units issued fundraising labels that could be placed on mail to indicate charitable support. Since those on active duty enjoyed free-franking privileges, they often placed these military stamps on their mail in lieu of regular postage. These stamps were duly cancelled by the field post offices. Different parts of a unit sometimes had their own stamps.
From Sulser Catlogue:
The soldier-stamps were not issued by the swiss-mail (PTT) but by the individual units. They were not allowed for non field-post pieces but they were authorized by the PTT. The designs had to be presented to PTT general administartion at Bern for approval (Armyorder Nr.102 from 16.12.1939). They were classified as charity stamps.
Armeebefehl Nr. 102 was issued:
1. Every unit may only issue one stamp until 1.9.1940, no variations and only one printrun!
2. All future designs shall be presented to the PTT directorate at Bern for approval.
Later on this order where supplemented with more rules to follow:
Armeebefehl Nr. 125 (26.4.40) changed the right of approval from PTT to the Generaladjutant of the Army's office.
Most remarkable are the later paragraphs of this order:
4.The printers which are printing the stamps are to be bound by contract with penalty clause to take care that no stamps are sold from the printers-stock. All essais and printing error's are to be destroyed at the spot and are forbidden to be brought into circulation.
5. printing plates shall be handed out to the commander of the issuing unit or be destroyed under personal observation of the units commander.
Armeebefehl Nr. 159 (28.1040)
Term definition for the no-variations rule from army order 102.
1. Each army unit down to Bat. and Abt. may issue one stamp per year of mobilization (timespan from 1.9. –31.8.). Only one single stamp in one printrun without any variations in colour, paper, perforation, text, picture (i.e. tête-bêche), gum, souvenier sheets, mini-sheets of 1,2,3,4 or more stamps or any other variation.
2. Only perforated blocks of 4 with plain white margin, without any aditional printings are not counted as a variation and are allowed even if singles of this stamps are issued .
3. Generaly overprints are not allowed. Only if a issuing unit has a large stock of last years stamps, it may be allowed by the Generaladjutant of the Army's office to overprint them as the stamp for the new year.
But not only the high command issued orders on the soldiers-stamps. Also the Fieldpostdirectorate had some important ruels on soldiers-stamps.
Order Nr. 10 (5.10.39)
The military charity stamps may be canceld with the troops standard cachet BUT NOT by the dated cancels of the fieldpost offices.
Oder Nr. 12 (24.10.39)
The military charity stamps are to be designed in size that a confusion with PTT stamps is not possible. Also no value is allowed to be printed on the stamps.
Collectors have to use an additional PTT franking on their letters.