Dear all,
Please find below an excerpt from the Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services with PD implementing rules.
Please have a look and discuss change proposals in the comments.
10. POPULATION DISTRIBUTION – DEMOGRAPHY
10.1. Spatial object types
The following spatial object type is specified for the spatial data theme Population Distribution – Demography: Statistical Distribution.
10.1.1. Statistical Distribution (StatisticalDistribution)
Set of measures describing how a phenomenon is spread within some part of the 2D world.
Attribute 
Definition 
Type 
Voidability 
inspireId 
External object identifier of the spatial object. 
Identifier 

areaOfDissemination 
The part of the 2D world the StatisticalDataDistribution describes. 
GM_Surface 

universe 
When distribution is related to a subset of the population and not the population in its whole, the literal description of the way this subset was defined. 
PT_FreeText 

domain 
The part of statistical knowledge the data refers to. 
PT_FreeText 

measure 
The measure concerned by the distribution. 
VariableValue 

measurementMethod 
The description of the statistic measurement method. 
StatisticsMeasurementMethodValue 

measurementUnit 
The unit of the measurement. 
UnitOfMeasure 

notCountedProportion 
The proportion of population of the area of interest that is not counted in any of its spatial components. 
Number 

periodOfMeasurement 
The date or period the observation has been taken, the data was collected. 
TM_Period 

periodOfReference 
The period when the data is supposed to give a picture of the area of interest. 
TM_Period 

periodOfValidity 
The period in which the data remains relevant. 
TM_Period 

beginLifeSpanVersion 
Date and time at which this version of the spatial object was inserted or changed in the spatial data set. 
DateTime 
voidable 
endLifeSpanVersion 
Date and time at which this version of the spatial object was superseded or retired in the spatial data set. 
DateTime 
voidable 
generalStatus 
The status of the statistical data distribution. 
StatisticalDataStatusValue 

Association role 
Definition 
Type 
Voidability 
value 
The statistical values composing the distribution. 
StatisticalValue 

classification 
Additional classifications used to split a total value of the described phenomenon. The StatisticalDistribution object will provide actually several distributions, one for each item of the used classification. When no classification is provided, the statistical value is the total population. 
Classification 

10.2. Data types
10.2.1. Classification (Classification)
A classification used for a statistical distribution.
Attribute 
Definition 
Type 
Voidability 
type 
The classification type. 
ClassificationTypeValue 

Association role 
Definition 
Type 
Voidability 
item 
The items composing the classification. 
ClassificationItem 

10.2.2. Classification Item (ClassificationItem)
An item composing a classification.
Attribute 
Definition 
Type 
Voidability 
type 
The classification item type. 
ClassificationItemTypeValue 

10.2.3. Statistical Value (StatisticalValue)
The pieces of datum of the distribution.
Attribute 
Definition 
Type 
Voidability 
value 
The value for the piece of datum. 
Number 

specialValue 
Some conventional string when value for the piece of datum cannot be provided: missing value, value hidden because of confidentiality. 
SpecialValue 

conventionallyLocatedProportion 
The proportion of population counted in the piece of datum but that cannot actually be physically located anywhere within the area of interest. 
Number 

approximatelyLocatedPopulationProportion 
The proportion of population count that doesn’t follow the common rule for location. ‘Population’ can be persons if persons are counted, dwellings if the StatisticalDatadistribution is about dwellings, etc. 
Number 

comment 
Free style comment about the value. 
PT_FreeText 

flags 
A set of onecharacter encoded comments about the data. 
PT_FreeText 

periodOfMeasurement 
The collection period of the statistical value. This period overrides the period specified in the associated statistical distribution. 
TM_Period 
voidable 
status 
The status of the statistical data. 
StatisticalDataStatusValue 

Association role 
Definition 
Type 
Voidability 
dimensions 
The part of the world the piece of datum refers to. Dimensions contains a description of the geographic location (2D dimension) together with possible additional dimensions when population counts are produced simultaneously for different individual characteristics. 
Dimensions 

Either the value or the specialValue attribute shall be provided.
10.2.4. Dimensions (Dimensions)
The identification of what the piece of datum refers to in terms of geographic location or individual characteristics.
Association role 
Definition 
Type 
Voidability 
spatial 
The spatial dimension of the statistical value. 
StatisticalUnit 

thematic 
The thematic dimensions of the statistical value. 
ClassificationItem 

10.3. Code lists
10.3.1. Classification Type (ClassificationTypeValue)
Code values for classification types.
The allowed values for this code list comprise any values defined by data providers.
Data providers may use the values specified in the INSPIRE Technical Guidance document on Population Distribution.
10.3.2. Classification Item Type (ClassificationItemTypeValue)
Code values for classification items.
The allowed values for this code list comprise the values of the following code lists or other code lists defined by data providers:
— Age By 5 Years (AgeBy5YearsValue): Code values for age by 5 years classification items, as specified in the table below.
Value 
Name 
Definition 
05 
05 
0 to less than 5 
510 
510 
5 to less than 10 
1015 
1015 
10 to less than 15 
1520 
1520 
15 to less than 20 
2025 
2025 
20 to less than 25 
2530 
2530 
25 to less than 30 
3035 
3035 
30 to less than 35 
3540 
3540 
35 to less than 40 
4045 
4045 
40 to less than 45 
4550 
4550 
45 to less than 50 
5055 
5055 
50 to less than 55 
5560 
5560 
55 to less than 60 
6065 
6065 
60 to less than 65 
6570 
6570 
65 to less than 70 
7075 
7075 
70 to less than 75 
7580 
7580 
75 to less than 80 
8085 
8085 
80 to less than 85 
8590 
8590 
85 to less than 90 
90+ 
90 
90 and more 
9095 
9095 
90 to less than 95 
95+ 
95 
95 and more 
95100 
95100 
95 to less than 100 
100+ 
100 
100 and more 
— Age By Year (AgeByYearValue): Code values for age by year classification items, including one value for each oneyear interval. The first value shall be ‘01’ with the label ‘01’ and the definition ‘0 to less than 1 year’, and the last value shall be ‘100+’ with label ‘100+’ and the definition ‘100 years or older’.
— NACE Code (NACECodeValue): Classification of economic activities according to Eurostat NACE, as specified in Regulation (EC) No 1893/2006 of the European Parliament and of the Council and narrower values defined by data providers.
— Gender (GenderValue): Gender of a person or group of persons, as specified in Section 4.6 of Annex I.
10.3.3. Variable (VariableValue)
Code values for variable names.
The allowed values for this code list comprise any values defined by data providers.
Data providers may use the values specified in the INSPIRE Technical Guidance document on Population Distribution – Demography.
... continued in the comments
10.3.4. Statistics Measurement Method (StatisticsMeasurementMethodValue)
Code values for statistics measurement method.
The allowed values for this code list comprise the values specified in the table below and additional values at any level defined by data providers.
Value 
Name 
Definition 
count 
count 
A simple count. 
relativeCount 
relative count 
A ratio combining two different kinds of statistical population. 
percentage 
percentage 
A proportion expressed as a ratio whose denominator is 100. 
median 
median 
The median. 
10.3.5. Status of Statistical Data (StatisticalDataStatusValue)
Code values for status.
The allowed values for this code list comprise the values specified in the table below and additional values at any level defined by data providers.
Value 
Name 
Definition 
definitive 
definitive 
A definitive statistical data value. 
final 
final 
A final statistical data value. 
preliminary 
preliminary 
A preliminary statistical data value. 
provisional 
provisional 
A provisional statistical data value. 
semiDefinitive 
semidefinitive 
A semidefinitive statistical data value. 
10.3.6. Special Value (SpecialValue)
Code values for special values.
The allowed values for this code list comprise the values specified in the table below and additional values at any level defined by data providers.
Value 
Name 
Definition 
confidential 
confidential 
The value is not provided for confidentiality reasons. 
unknown 
unknown 
The value could have been measured but was not. 
notApplicable 
not applicable 
The value would not have any sense. 
10.4. Layers
No layers are defined for the spatial data theme Population Distribution and Demography.
Mandatory comment for StatisticalValue:
Following up the discussion at the meeting: in the implementing rules the comment is listed as follows:
Attribute 
Definition 
Type 
Voidability 
comment

Free style comment about the value.  PT_FreeText 
In the data model in the TGs it looks like this:
comment has multiplicity [0..1]. Does it mean it can be omitted or should we file a change proposal to make it voidable?
OK, having a closer look at the IRs and the model it seems that IRs disregard multiplicity. But does that mean that ALL attributes that have not been marked "voidable" are mandatory according to the IRs, even if they have [0..1] multiplicity?
StatisticalValue has a {valueOrSpecialValue} constrant which translates to IR as "Either the value or the specialValue attribute shall be provided". So one might think that one of these are the only mandatory attributes.
StatisticalDistribution, however, has no constraints and attributes with multiplicity [0..1] are not voidable. So, reading only the IRs, one might think that ALL atributes are mandatory.
INSPIRE datasets are validated with the xsd schema generated from the model described in the TGs, so in terms of validation we're OK, but it's the IRs that set the official requirements for Member States, so if they list [0..1] attributes as mandatory, we should point this out now.