in placefor _that sector_ that violate market access and/or national treatment, respectively. Such limitations and exceptions must be specified by mode of supply. As there are four modes of supply, there are therefore eight opportunities for GATS Members to avoid full application of market access/national treatment. In addition to the specific commitments, countries also make 'horizontal' commitments. These usually consist of a compilation of laws and policies that restrict the use of a mode of supply by foreign suppliers, independent of the sector involved. A policy that is often scheduled is an 'economic needs' test--laws or regulations stipulating that foreign service providers may contest a market only if domestic providers do not exist, or are unable to satisfy demand. Another example is a general licensing or approval requirement. In many instances such horizontal 'headnotes' simply involve a restriction on the inward movement of natural persons. Table 3 illustrates the format of the schedules. An entry of 'none' means a Member binds itself not to have any measures that violate a market access or national treatment for a specific sector/mode-of-supply combination; 'unbound' implies that no commitments are made for a particular mode of supply.'<sup>8</sup>

# _Quantifying the specific commitments: conceptual issues_

To assess the schedules, a quantitative measure is required that allows for cross-country comparisons. In principle this requires a mapping of schedules onto a scale that is invariant across countries. A first step could consist of determining the total value of output represented by a Member's scheduled sectors as a proportion of its GDP. If country A schedules only 5 % of it's service sector in GDP terms, while country B schedules 15%, one can say that in an absolute sense B has offered three times as much as A. This requires the use of a common sectoral classification and output data that is consistent with this classification. The Group of Negotiations on Services (GNS) established a list of services. This list--reproduced in Annex 1--has been used by Members in scheduling commitments. It is based on the Central Product Classification (CPC), with the exception of communication and financial services, where a GNS-specific breakdown of activities was deemed necessary.

Unfortunately, no countries collect/report disaggregated data on the basis of the CPC, as it has only been developed recently. Many countries only report GDP data for 5-10 service sectors. Obtaining the requisite output data for all GATS Members, even for the 11 major service categories distinguished in the GNS list, is a major endeavor. It has not been undertaken in this paper. In part this is because to be meaningful, indicators of sectoral coverage must incorporate information on the restrictiveness of the measures that are maintained with respect to national treatment and/or market access. This is much more important--but also much more difficult--than determining the 'production weights'.

' Most Members do not list horizontal restrictions on cross-border supply or consumer movement. It is not clear whether this implies that they have bound themselves. It should also be mentioned that the GATS allows for 'additional commitments' to be made going beyond national treatment/market access. Virtually no use was made of this option, and it will be ignored in what follows.

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