Horizon Label Service indicators - explanation

I've been asked to explain the various codes used on the Horizon labels, our own web page describing these having fallen far behind, sadly.  Updates added in blue following publication of a list on the Stampboards forum.

I've no idea of the full range of codes originally used when the system started in 2002.

There was 2ND and 1ST for 2nd class and 1st class inland mail, and P for inland Parcels.
SD was used for Special Delivery, but Recorded Delivery passes as 2nd & 1st as it has no priority treatment.    A for Airmail, and S for Surface were other commonly found usage, though as these went on international mail there are not many to be found here.

From 2003 the indicators went to lower case and as the normal designations didn't comply with Welsh language designation, so for bilingual labels we have different ones for Welsh offices: 2nd 2il 1st 1af. 

AX is used for the Airsure service, but no special indicator is used for International Signed For, even though both are used as substitutes for the obsolete Registered service.   

There are many service indicators that are rarely seen by the public, for reasons which will become obivous.  The indicators had to change when Pricing in Proportion (PIP) came into effect in 2006, to take account of Large Letters and Packets, though even some of these have changed over time, 1LL, 2LL and BLL being changed to 1LG, 2LG, BLG.  This current list may not be exhaustive, but includes the more common ones.  The 'B' indicators in the first three categories, are for British Forces mail, which is 1st class but is carried under PIP rules:

1st - only for Articles for the Blind as no labels are produced for items under 100gr and any other mail over 100gr is a Large Letter.

1L/2L/BL - 1st/2nd class Letter -  restricted to Recorded Signed For (small) letters

1LG/2LG/BLG - 1st/2nd class Large Letter (no longer applied to items under 100gr)
1PK/2PK/BPK - 1st/2nd class Packet

SD - Special Delivery 9am and 1pm services
SP - Standard Parcel
PE - International Economy Parcel
PS - Standard International Parcel
BF - BFPO Parcels 

A / SU - Airmail, Surface mail to all countries
AAX - Airsure service (limited to about 30 countries)

FP - Fully Paid Reposted Underpaid Airmail (items returned to sender for additional payment).
MOR - Mail Order Return (one that is unlikely to be sent to a private house!)
RPR - Packet Post Return (Limited to Value of Recorded Signed For)
FF - I've not seen one of these, but I assume that it may be for Forces Free, sent to British Forces 'in theatre' in Iraq and Afghanistan.  Confirmed as Forces Freepost.

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