Review iOS LMT rules

[bretg]

A few years back in prebid/prebid-server#1699 Prebid Server implemented a workaround to an IOS issue.

It looks like we designed this carefully to be future-proof, but would like to ask the mobile committee to re-review. Thanks.

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1. If PBS receives a request with the following attributes: app object exists, device.os = “iOS”(lower case value before matching), device.osv = “14.0" or “14.1” the following requirements apply:

• 1a. If device.ifa = null or “” (empty string) or “00000000-0000-0000-0000-000000000000”, set device.lmt = 1
• 1b. Else, set device.lmt=0, in the request to bid adapters

2. Else if PBS receives a request with the following attributes: app object exists, device.os = “iOS”, device.osv = “14.2” or greater the following requirements apply:

• 2a. If device.ext.atts = 3, set device.lmt = 0, in the request to bid adapters. ATTS 3 is "authorized"
• 2b. Else if device.ext.atts = 0, 1 or 2, set device.lmt = 1, in the request to bid adapters. ATTS 0, 1, and 2 are "unspecified", "restricted" and "denied" respectively

3. Else, use device.lmt in the request

[jsligh]

@bretg I looked through the code and I believe this is still correct.

[bretg]

Thanks for confirming @jsligh