Many PPs exhibit some amount of lexicalization or idiomaticity.
This is especially true of PPs that tend to be used predicatively.
In general it is extremely difficult to establish tests to distinguish idiomatic PPs from fully productive combinations.
However, the usual criteria apply for the supersense analysis.

For example, if the PP answers a <i>Where?</i> question, it qualifies as [ss Locus]; whereas qualitative states usually have [ss Characteristic] as the scene role:

- [ex 001 "He is [p en/out_of Locus] town. ([ss Locus])"]

- [ex 002 "The company is [p en/out_of Characteristic--Locus] business. ([ss Characteristic--Locus])"]

See further discussion at [ss Characteristic].


## PP Idioms vs. Multiword Prepositions

A PP idiom is a fixed or semi-fixed expression consisting of an adposition plus its complement 
(usually an NP, AdjP, or AdvP), which must be a complete phrase. 
In some of these expressions the complement may take variable modifiers (e.g., *[p en/on]\_ ONE's \_own*: see [ss `$]). 
The PP idiom as a whole does not take a complement (is intransitive). 
A fixed expression ending in a transitive preposition like [p en/of] or [p en/as] 
([p en/in_search_of], [p en/as_long_as]) requires a complement, and thus is not a PP idiom.[^2] 


## Reflexive PP Idioms

Certain idiomatic constructions involve a preposition that requires a reflexive direct object.

**PERFORM-ACTIVITY <i>for</i> oneself.**

###1. When something is done for one’s own benefit rather than someone else’s:

- [ex 003 "I took a vacation [p en/for Beneficiary] myself ([ss Beneficiary])"]

###2. When something is done in a way that affords direct rather than second-hand information:

- [ex 004 "You should try out the restaurant [p en/for Agent--Beneficiary] yourself! ([ss Agent--Beneficiary])"]

**PERFORM-ACTIVITY <i>by</i> oneself.**

###1. When something is done without accompaniment (the negation would be <i>[p en/with] others</i>):

- [ex 005 "I had lunch (all) [p en/by Ancillary] myself [‘alone’] ([ss Ancillary][^1])"]

###2. When something is accomplished independently, without assistance:

- [ex 006 "I made the decision (all) [p en/by Manner] myself. ([ss Manner])"]

- [ex 007 "The computer rebooted all [p en/by Manner] itself. ([ss Manner])"]

**BE <i>by</i> oneself.**

Alone; unaccompanied:

- [ex 008 "I am [p en/by Ancillary] myself right now. ([ss Ancillary])"]

[^2]: Infinitive marker [p en/to] counts as a transitive preposition for purposes of this definition.
[^1]: Though <i>myself</i> is not literally accompanying <i>I</i>, the PP as a whole describes the nature of accompaniment (or lack thereof).